View Poll Results: test pipe or cat
test pipe
11
64.71%
cat
6
35.29%
Voters: 17. You may not vote on this poll
test pipe
#14
#17
I have a funny story. Everyone always says on NA that test pipes don't give more HP. I dyno everything when I get a chance. I took my test pipe for testing the A/F ratio on my car with a wideband after changing cams in my car. I asked the dyno operator if I was going to be tempted to run the test pipe on the street. He said he had never seen a test pipe give much if any power. After tuning I put my cat back on and did another pull. HP was basically the same but I lost 15whp with the cat at 5k rpm. This is after both of my cams engage. I was shocked.
#19
I have read it and heard it several times, some cars have actually lost HP after removing the cat. Even on my car I did not gain any peak HP. The dyno operator said the same thing and he has dyno'd tons of cars. He was also surprised that I gained 15whp @ 5000rpm on a 185whp 2.0 liter 4 cylinder engine. I am not talking about gaining 1-2 whp that is not a big enough change to get excited about on a dyno. Cars can vary that much from run to run with no real changes having been made.