My car is putting out around 315 HP right now. The guy I bought the car from had true dual 3.5 inch pipe (yes 3.5 inch) put on (no mufflers)

Sounds great but I'm worried about performence loss (esp low end, not enough backpressure... etc...)

So what do you think? Am I losing low end performence or should I keep the setup I have?

 

we're not mind readers you gave no facts on the car other than the exaust.

 

1. Backpressure causes lost performance, it does not increase low-end torque. Anything you can do to reduce restriction(backpressure) after the headers will increase performance.
2. Dual 3.5" pipes would be oversized on a 502, it's overkill on a street car. A single 3.5" system will be fine for the hp level you are at. Get a system that tucks along the stock path and enjoy some ground clearance.

 

Oversized for a 502 putting out under 450 hp My friend's 454 is putting out around 500 hp and runs so much better with dual 3.5 spintechs rather than dual 2.5 flowmasters. Open headers it ran a best of 12.01, with the flowmaster setup it ran a 12.4x. He hasn't been to the track again since the new exhaust but it does get up and go better now.

 

A Kenworth with a 800 cid turbo-diesel I could see needing dual 3.5's. A 500 hp bb could do quite well with dual 2.75's. At that point the muffler's are more of a restriction than pipes ever will be. Your friend probably saw more of an improvement from swithching to the Spintech's, than he did from the increase in pipe size.

I ain't knocking anyone for having dual 3.5's, it's not my car - nor my worry, but once you get past dual 2.5's on a small-block, diminishing returns should play a part in your decision of how big you want to go. If I lived in mortal fear of speed bumps and potholes, I'd question whether the extra 5 - 7 hp(gained by going from dual 2.5's to dual 3.5's) is worth it. If the car is mostly for the strip or the occassional cruise night - fine, but if it gets driven regularly - not so fine. Just my opinion tho,... we all make the sacrifices we are comfortable with.

[This message has been edited by 88IROCs (edited September 28, 2001).]