Your engine sucks up some of the exhaust if the gases are not able to escape, this cause's iregular detenation & valve burning. & yes single is better.

 

I am not really following this. How is it bad for the car if it makes more power?

 

ok it only make power up-top and of course evasive (the proven dyno) will post dyno graph's showing major gains, they sell it..duh? what would you do if you were selling a product? but hey I could be wrong, seriously. But from dyno's Ive seen in person, a 68mm+ exhaust will make you lose power & torque at low & even mid-rpms and steadily increase as it reach 4,500-6,000rpm depending on setup & vehicle.

 

Good read... I believe the happy spot for N/A is 70mm, anything more and Tq #'s suffer dramatically. This is stricly based on memory.

80mm would be best for F/I.

An exhaust at 60mm bolted on and off against a 70mm would be a fact.

 

60mm is stock, i think 2.5 inch is the sweet spot, but then again it depends what other modifications you have, if you have lets say ITB's, obviously you have more output so you could go larger.

I made a post so we could discuss this and let the OP finish his post..lol

 

do you have dyno graph's to prove your theory? i've seen dyno graph's for the 70mm exhaust's not just from evasive or a-j racing but from members who have dyno graph's. and i've seen that the 70mm single makes 5-10 more horse power than a 63mm single. and i was just wondering what your expert thoughts were on how that happened. and could you explain to me why f1 cars are straight header?

 

No i dont..Show me the graph's and what modifications they had...I never said they didnt make power, they're just not efficient. You really dont make power at low-mid rpms, I know you gain up-top. F1 cars are fully built engines and are replaced/rebuilt every race. You too could run open header.

 

actually they have to last 2 race week ends without rebuild

 

just the last 2 hangers that are over the mufflers , i got ap1 hangers but iv read on hear that the ap2's work fine

 

I'm interested in that Exhaust for MY07 S2000. Can you give me a price quote shipped to 94560. Thanks.