[5erman]

So guys I have a 07 530 n52 255 hp engine and our exhausts are a bit different. my stock exhaust is

Cat1===cat2=====<resonator--------------------------OEM Muffler

== is dual 2 inch piping that uses a y pip to enter resonator
then a single 2.75 inch pipe leaves the resonator all the way to the oem muffler.

I added an RPI exhaust months ago so that it looked like this

cat====cat======<resonator-----------///////////RPI muffler

the difference was that the rpi tubing was 2.5 inches so it connected to the stock 2.75 piping after the resonator.

now this weekend i did this
cat1=====cat2=====>-------------------------------------------RPI

So basically cat was taken out and at the y pipe a single 2.5 inche pipe went straight and connected to the RPI 2.5 inch pipe and muffler.

I love the sound and the low end performance is mean! big difference as I feel it gets the velocity flowing faster earlier on when gases are not as hot on the bottom end and the smaller piping creates more velocity.

My question is do you think this will hurt tiop end performance using a little bit less than stock 2.75 piping? The resonator was HEAVy and had a ton of bafling and empty space so who knows what that did to kill velocity-it definetly slowed speed down in there.

The sound is about 2 times the RIP exhaust alone-same in quality just louder-amazing.

Do you guys know what the 330 or 328 exhaust pipe diamter is after the resonator to the rear muffler

[DimSum]

Basicly, you'll be getting better torque and low-end. Who really needs the top end on this car? Unless you do a lot of highway driving and want to save gas then maybe, other wise getting a quicker low-end and acceleration is a must for the N52.

If your not happy with your top end then try doing 2.75 to the rear muffler.

[Alexander]

I did this back when I had my 328i. Loved the sound.