I was just reading in another section that dropping VTEC below a certain level does not help unless you have a test pipe. I did a quick search and didn't find anything that specifically addresses this for FI. I have read that exhaust that is too free flowing can actually hurt power potential for low boost SC'd S's.

I picked up a test pipe off craigslist a few months ago and it's been sitting on a shelf in the garage. Will it help my mid-range if I throw it on?

I've got a Comptech Novi 1000, 10 lbs of boost, CT Engineering cat back (stock cat) with about 350 whp.

Thanks.

 

The only way to know for sure is put it on a dyno with the cat on, then take it off put on the test pipe and dyno it again. When I had a SC setup, I had a test pipe...no issues, but I could not tell you if there was a difference, I changed it along with the SC install.

 

If you are not babying your car, it is very likely within a couple years your cat will be hurt. I encourage you to check it after a year.

 

taking my cat off made a huge difference! the stock cat cant cope with the extra flow for long I think I got 4-5k miles before it started going south and that was at 7 psi now at 13 psi and wouldn't think of running a cat full time unless I built my own with a very large core.

 

You guys talking about high flow cats or oem.

Been running a hfc for a while but i wanted to switch to a rest pipe. Just can't stand the smell.

 

I swapped for the test pipe a few days ago. Butt dyno saw little to no change, maybe a little better mid range. No noticeable smell issues. Running a hair leaner under low loads 3 to 5,000 rpms. Running richer (low 11's) over 7,500 rpm's with the black cloud. A couple times I got just a little farting backfire at 4,000 rpm's when vtec hits. Sound changed a bit, already used to it. I ran a few logs and everything looks safe, but I'll need a retune.

The cat looked to be getting clogged. The S had the base kit for about 12,000 miles with higher boost for about 5,000 miles now.

 

I wanted to avoid the retune if I had to darn