Altima Coupe 3.5 manual - Exhaust System

[coopbuff]

I'm in the process of installing a Borla muffler on my car and noticed that the intermediate pipe has a short section of it, that is factory crimped or flattened approximatley 50% for no obvious reason.What purpose does this serve? Tuning? Backpressure? or to limit the performance.I would like to get the most out of my engine, can I remove this and have a pipe made with no restriction?Thanks!Mike

[CoupeVQ35CVT]

2 words - ground clearance.

If you look where the stock y-pipe right after the header is it is also crimped flatter so it doesn't stick out as much. Honestly my own catback (ebay brand) gets away with using a normal round pipe all the way and I have not had any clearance issues.

The flat part is probably limiting a miniscule % of power but go for it and replace it while you're at it . I think the better improvement would be right after the stock y-pipe up front. Back pressure would only hurt performance but since it's crimped more oval and not exactly bottle neck shaped I think it doesn't do much at that area.