I picked up chimmike's Nismo exhaust (minus y-pipe) over the weekend (which is in GREAT shape, especially after I shined it up, thanks man), and ordered up a Nismo-replica y-pipe, 2.5" inlets with a 3" outlet. I'm pretty anxious to put it on the car to see how she sounds, but had a question first.

I currently have a set of Helix non-resonated test pipes sitting around that I had installed on my current Injen TD straight-tip for a little while, but with the Injen starting off loud in the first place, they made the exhaust a little TOO loud for my tastes. I was thinking about putting them on at the same time as the Nismo, just to see if I liked them or not, but the difference in piping diameter is making me wary. The Helix test pipes are 2.25" diameter, while the y-pipe I have on order from Intense Motorsports is 2.5" inlet. Will there be any problems with flow going from a smaller diameter to a slightly larger? I know that you're supposed to attempt to match exhaust piping as much as possible.

 

there might be a slight bit of turbulence in the flow, but otherwise it'll be fine and definitely better than running stock cats.

I can't guarantee it's gonna sound great, but ya never know until you bolt 'em up


yeah that nismo sure shines when you put some elbow grease into it if it's super dirty. It had a good polish a few weeks ago for Zfest so a simple clean/polish prolly brought it to the new-polish condition

 

Thanks for the input. I figure it's like an hour job to swap out the cats again if I hate the test pipe sound, so no big deal. I'll try to take some sound clips to post up.

Yeah yesterday I hit the exhaust / tips with that Eagle One NevrDull for about 10 minutes... she looks great! Can't wait to bolt her up.

 

Careful....... turbulence most often than not = rasp/drone. Good luck thought and post a clip.

 

+1. I would prefer that you go from a 60 to 70 mm pipe rather than 70 to 60 mm. But the performance difference is minor.

 

From shopping around, there are few ways around this issue. very few.