Most all LDP's are fine. Catted full Downpipes are a bit better but VERY expensive, much harder to install, and a bit louder. LDP's are an excellent value and upgrade with a supporting CBE.
The Fast Intentions "system" being the best power gains, but expensive and a long wait. The wait speaks for itself.
The bigest restriction are the secondary cats which the LDP eliminates.
If stock cat-back, go with Megan's 2.5''. The variance from the OEM mid to 2.5'' will cut down on the chances of leak. AMS includes an adaptor place for their 3'' but it's not the best way to do it.Can you make a recommendation for one that won't be loud in the cabin? This is my first experience with DP's and I don't know what to expect. My coworker put a full Stillen exhaust on his Q50 Red Sport with lower down pipes and it's so loud in his car that I can't ride with him.
This is why a 2.5" or even a 3" with a 2.5" exit works so well. Less turbulence. Well unless you have a 3" X-Pipe, or CBE which are loud, to loud for me. Not all that much difference in performance. But some people like that. Each to their own. Diversity is a good thing.Here is my 3" AMS lower downpipes bolted to stock Y pipe. I don't have the stock exhaust anymore but here is just a visual for comparison.
Interesting that he had that experience, because @Ddnspider has CATLESS full downpipes, megan Y and tanabe mid and his car is smooth.Adding a Y pipe wont change sound much. Changing the stock midpipe will. The stock resonators do a better job than anything aftermarket at keeping things quiet. I talked for a while to another member MoonSport on here. He did the same thing. Replaced LDP, used a Megan Y and either a Tanabe or a Megan midpipe and it was just to much for the stock muffler. The LDP and Y pipe the stock muffler was ok but remove the stock resonators with some larger piping and aftermarket resonators and it rasped through the stock muffler. He bought a HKS axle back to get it right. That axle back alone is $1,100 dollars. So just my advice if you are keeping the stock muffler leave the stock midpipe or get the FI resonated CBE.
Here is a link to the thread. Look at the 5th post down....
Serstylz2 are you running map 7 on you JB4 or are you running higher than 7psi in a custom map.I am just curious if 7psi over stock will get you 16.8psi total. That is where I would like to be at. Below 18 but real close or at 17.... Thanks....
Im thinking of the same setup but going Megan LDP, and Rev9 mid/y pipe non resonated to add a touch of sound. The stock muffler should keep it nice and quiet.I have AMS 3" LDP dropping into the OEM exhaust system. No change in sound inside or out of the car. Here's a video I made for evidence.
I plan to upgrade the Y pipe and possibly the midpipe and hoping that the sound will remain muted