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HKS Resonated Lower Downpipes Review

49K views 294 replies 38 participants last post by  DougK 
#1 · (Edited)
Hi guys, thought I’d throw this up here since I couldn’t find any feedback before I purchased.
So I initially installed a mufflerless catback system on my Red Sport paired with the AMS lower downpipes. It was a big mistake for me. Thought I wanted loud, turns out I didn’t at all. I made it four miles down the road before I turned around and had the oem muffler reinstalled with the AMS downpipes still. As effective as they were, I didn’t really care for the amplified turbo sound coming in cabin so I took a shot on the HKS.
Initial response was couldn’t be happier. If you want more power without sacrificing luxury, these are the way to go. They aren’t any louder in the slightest bit at cruise or wide open throttle. Sounds stock.
As far as build quality and fitment, I’d give them 5 stars. My installer rated the ease of install at 9 out of 10.
And lastly for performance, this was difficult for me to judge at first. I had them installed at the same time I was supposed to get an Ecutek tune. Unfortunately there was an issue on not having the right flash for my specific early year model, so I had downpipes installed but was down JB4 when I left. That was removed because I had it sold the next day. So needless to say I couldn’t compare it to before I brought it in so I am comparing to stock. It has definitely picked a lot in the low end. I’m getting wheel spin where I haven’t previously on stock boost levels. And most impressively to me is that partial throttle acceleration, like as used for lane changes. The car just floats effortlessly as the turbo spools quicker at lower rpms.
I’m a fan of the 2.5” over the competitors 3” variants. I’ll sacrifice a little horsepower for torque since the vast majority of my driving is not spent at wide open throttle. And IMO, 3” is overkill on these tiny turbos and my tuner agreed with that.
Again, couldn’t be happier with them. I should be getting the tune in the next week or two so I’ll be sure to update and post the dyno graph for all who are interested.
 

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#2 ·
Thanks for the detailed review and pictures. So it looks like these remove the secondary cats and replace with a resonator to keep the noise tame. Is that correct?
 
#5 ·
Yes that is correct.
Im about to order these soon.

Question: are those stickers heat resistant or were just there during photo shoot?
Honestly not sure as I didn’t install personally. I’ll see next time I’m on a lift lol.
Thanks for the review. Did you happen to obtain weights of the HKS DPs before install? What CB do you have?

I do still think the bang for the buck purchase is the Megan Racing DPs but it's good to have options. And, of course, the HKS are resonated. I'm not totally sure but I suspect noise output would be similar with resonators in either the DPs or the CB. Did you contemplate that combo? - Keeping your AMS DPs and going with a resonated exhaust?
So the shipping weight was 16lbs. I did have the Ams downpipes on a resonated afe takeda mid/y pipe combo exiting out of the stock muffler. There was still a lot of cabin noise coming through. If sleeper is the goal, these are hands down the winner.
Right now, these are on stock catback. If Fast Intentions does a nice Black Friday sale, that may not be the case much longer.
All set for tune on this Friday so I’ll be sure to update with dyno.
 
#4 ·
Thanks for the review. Did you happen to obtain weights of the HKS DPs before install? What CB do you have?

I do still think the bang for the buck purchase is the Megan Racing DPs but it's good to have options. And, of course, the HKS are resonated. I'm not totally sure but I suspect noise output would be similar with resonators in either the DPs or the CB. Did you contemplate that combo? - Keeping your AMS DPs and going with a resonated exhaust?
 
#25 ·
When it comes to sound volume and rasp. You always want to have the resonator as close to the source as possible. You can see the Engineers at HKS put that resonator right at the mouth of the downpipe bc that is where the increase in sound volume would occur.

You can quiet a standard downpipe with resonators in the exhaust, but it will be less efficient doing it that way. Using these with my MBRP exhaust, and it sounds virtually the same as it did with stock cats. It is a bit louder, and I love the extra turbo noise. but no rasp or drone which we all know is there with standard downpipes.

 
#6 ·
Awesome good luck. I have a Stillen CB awaiting install. I am nervous that it might be too loud with no resonators, fairly small mufflers, and my existing non-resonated MR LDPs. We shall see...
 
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#7 ·
So you are running lower down pipes with factory exhaust?

You get torque but no HP based on my past experience (different platform), and it may not be a good idea for your turbos long term.

It would be better to run a quiet catback and leave the factory downpipe.

Thanks for the review nonetheless. It is a quality piece.
 
#9 ·
Any reason you aren't waiting for the catback before the tune?
Yes I have the ldps on the factory exhaust right now. Only reason, I really want to hear some systems in person before I pull the trigger again. If there’s any FI Black Friday deals, there’s a 99% chance I’ll place an order. I have a meet with some local guys this weekend so I’ll get to check out some other cars.
No particular reason I’m waiting on the catback other than wanting to hear some systems in person. It’s definitely on the list for sure. FI catback and Z1 built LSD on next up for the car. I guess tomorrow’s dyno will determine that order.
 
#10 ·
EcuTek tuned at SOHO Motorsports in Charlotte, NC. Graph attached. I’m thoroughly happy. She’s a monster on the streets and boost is definitely coming on much quicker with the LDP’s.
 

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#13 ·
Thanks for sharing Alex. I like the 10 / 15 / 20 PSI comparison.
 
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#15 ·
Which system do you think is quieter? The hemholtz Infiniti axelback is beautiful and I was contemplating running it behind a Tanabe y and resonated midsection. Truth is, I drive tractor trailer 60hrs a week for work, so I couldn’t be happier with how quiet the stock exhaust is on my ride home. If I could find a full 2.5” system that sounded no different at all I’d opt for that in a heartbeat. Being tuned running higher boost and upgraded intakes, I really want to create an equilibrium and cancel out the restrictions on the back end though.
 
#19 ·
The FI CBE w/resonators and touring mufflers is pretty quiet too yet provides the performance. I did turn off ASE in the diagnostic menu though.
 
#20 ·
+1 to Avedis53's comments.. I was very weary of changing out my exhaust b/c I'm a bit older and didn't want to own a rice rocket. I settled on the FI resonated cat back and it's perfect for my needs. Very minimal interior noise but sound comes on when you step on the accelerator.
 
#21 ·
Hi guys, thought I’d throw this up here since I couldn’t find any feedback before I purchased.
So I initially installed a mufflerless catback system on my Red Sport paired with the AMS lower downpipes. It was a big mistake for me. Thought I wanted loud, turns out I didn’t at all. I made it four miles down the road before I turned around and had the own muffler reinstalled with the AMS downpipes still. As effective as they were, I didn’t really care for the amplified turbo sound coming in cabin so I took a shot on the HKS.
Initial response was couldn’t be happier. If you want more power without sacrificing luxury, these are the way to go. They aren’t any louder in the slightest bit at cruise or wide open throttle. Sounds stock.
As far as build quality and fitment, I’d give them 5 stars. My installer rated the ease of install at 9 out of 10.
And lastly for performance, this was difficult for me to judge at first. I had them installed at the same time I was supposed to get an Ecutek tune. Unfortunately there was an issue on not having the right flash for my specific early year model, so I had downpipes installed but was down JB4 when I left. That was removed because I had it sold the next day. So needless to say I couldn’t compare it to before I brought it in so I am comparing to stock. It has definitely picked a lot in the low end. I’m getting wheel spin where I haven’t previously on stock boost levels. And most impressively to me is that partial throttle acceleration, like as used for lane changes. The car just floats effortlessly as the turbo spools quicker at lower rpms.
I’m a fan of the 2.5” over the competitors 3” variants. I’ll sacrifice a little horsepower for torque since the vast majority of my driving is not spent at wide open throttle. And IMO, 3” is overkill on these tiny turbos and my tuner agreed with that.
Again, couldn’t be happier with them. I should be getting the tune in the next week or two so I’ll be sure to update and post the dyno graph for all who are interested.
Thank you the great review. I'm actually looking into purchasing these downpipes along with a FI resonated CBE but am now a little worried that it will be too quiet. I want something louder than stock but not super loud. Maybe FI downpipes with resonated CBE? Any thoughts?
 
#24 ·
So just to update. I DID put in an order with fast intentions for the resonated touring system. It’ll be a few weeks but I’ll be sure to make some videos of the system paired to these downpipes. If you’re afraid it may be too quiet you could always get the non resonated version. The nice part about that is, if it ends up being too much for you, you can go to a reputable local muffler shop and they can add resonators after the fact.
 
#29 ·
I picked up the ARK Grip exhaust and it is really quiet as well. Perfect since I have a wife that hated my STI and was completely against anything that rumbled. The FI resonated system is also very nice. I got the ARK on black friday deal with 1560 shipped. Couldn't beat that!
 
#32 · (Edited)
Here's a short video...For some reason the Iphone cuts out and lowers the volume when it returns. Anyhow, its just ever so slightly louder than stock. It gets even quieter when warmed up.

EDIT: I think I figured out the volume thing and will remake a new video. Can't anymore tonight. My wife is going to get pissed if I keep honking the horn and turning the car on ?

 
#33 ·
Sounds really nice! No resonators on mid-pipe right? Is this with stock catted lower downpipes? Definitely upload another vid and blow some revs. Great deal with the Black Friday sale.
 
#37 ·
Thanks Wf. Wouldn't lower gear (higher RPM) = louder?
 
#40 ·
Yes, I think I read your 'when' as a 'than', sorry.
 
#39 ·
Sounds great @Windforce !! Nice clean growl without being obnoxious. That signature Infiniti “purr” is back. Now time to shove some extra boost in it hahaha!
 
#45 ·
Hi guys, thought I’d throw this up here since I couldn’t find any feedback before I purchased.
So I initially installed a mufflerless catback system on my Red Sport paired with the AMS lower downpipes. It was a big mistake for me. Thought I wanted loud, turns out I didn’t at all. I made it four miles down the road before I turned around and had the own muffler reinstalled with the AMS downpipes still. As effective as they were, I didn’t really care for the amplified turbo sound coming in cabin so I took a shot on the HKS.
Initial response was couldn’t be happier. If you want more power without sacrificing luxury, these are the way to go. They aren’t any louder in the slightest bit at cruise or wide open throttle. Sounds stock.
As far as build quality and fitment, I’d give them 5 stars. My installer rated the ease of install at 9 out of 10.
And lastly for performance, this was difficult for me to judge at first. I had them installed at the same time I was supposed to get an Ecutek tune. Unfortunately there was an issue on not having the right flash for my specific early year model, so I had downpipes installed but was down JB4 when I left. That was removed because I had it sold the next day. So needless to say I couldn’t compare it to before I brought it in so I am comparing to stock. It has definitely picked a lot in the low end. I’m getting wheel spin where I haven’t previously on stock boost levels. And most impressively to me is that partial throttle acceleration, like as used for lane changes. The car just floats effortlessly as the turbo spools quicker at lower rpms.
I’m a fan of the 2.5” over the competitors 3” variants. I’ll sacrifice a little horsepower for torque since the vast majority of my driving is not spent at wide open throttle. And IMO, 3” is overkill on these tiny turbos and my tuner agreed with that.
Again, couldn’t be happier with them. I should be getting the tune in the next week or two so I’ll be sure to update and post the dyno graph for all who are interested.
Great write up and review! I have the hks to megan ypipe, to tanabe catback and has the perfect level of throatiness and volume. Quiet enough that my neighbors don't hate me and just a touch of character that the valet last evening asked me if I had an exhaust when giving my car back. Also before the comments I was in NYC on park ave and there where plenty of nicer faster cars he could've took for joy ride, but it all honesty it went in an elevator and was parked. I never seen that in the city before...
 
#46 ·
Mrs. Avedis53 gave her approval to add a HKS LDP if I want to. Now all I have to do is get over my " it's going to be too loud" apprehension in doing this and buy it.
 
#47 ·
Nice, enjoy A53! I suspect you'll be ok with all those reso' and nice big muff's.

I removed my brace to see how things would sound/feel without my midpipe resting in the brace - and was going to drive her to work today - but it was raining so I took my TL instead. Doh!
 
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