ITRCA

you know how the mugen exhaust necks out from the cat to the resonator at 2in , and then at the end of the resonator its a little bigger through out the whole system. can i cut the part before the resonator off and weld bigger piping on it or does the resonator start at 2in and gets bigger at the end of it???

Call King Motor sports, they are likely going to be the only people that will know the internal piping diameters half way down the B-pipe. not sure if they'll even waste the time finding out if they don't......

it is 2" inside the muffler from the loop.

Not sure about the B-pipe

Every JDM cat-back exhaust system (except 1 or 2 straight through and under-the-axle design) will have small bottlenecks in the b-pipe. Why? Maybe it's to produce a desirable flow characteristic which can't be achieved by having a straight pipe design. Possibly, bottleneck is good for throttle response and/or midrange gains.

All in all, I wouldn't chop up Mugen exhaust to eliminate the bottle-neck. Mugen knows what they are doing... it's not there for aesthetic reasons.

I wouldn't chop it up either but I don't think I would put it first on my list.
Or even 2nd. For the cost I can buy a lot more parts and I don't think the ITR exhaust is a huge weak point.

does your mugen exhaust make a vibration sound when driving?

Cosworth wrote:Every JDM cat-back exhaust system (except 1 or 2 straight through and under-the-axle design) will have small bottlenecks in the b-pipe. Why? Maybe it's to produce a desirable flow characteristic which can't be achieved by having a straight pipe design. Possibly, bottleneck is good for throttle response and/or midrange gains.

All in all, I wouldn't chop up Mugen exhaust to eliminate the bottle-neck. Mugen knows what they are doing... it's not there for aesthetic reasons.

Bottleneck in the b-pipe after the cat is to slow down the flow just after the cat to maintain the temperature of the car...