exhaust size ? - Lateral-g Forums

lukky 71 · #1 01-12-2011, 08:02 AM

im building a 71 camaro with a 468 bb. flowmaster offers 2 kits. one with a crossflow 80 series muffler that tucks over the rearend. the other has 2 flowmaster 50 series mufflers that are under floorboards. both have mandrel bent 2.5 pipes. which kit is better and is mandrel bent pipes better than 3" bent pipes. this engine is 550 hp. i know it needs to flow well. thanks for any help.

DRJDVM's '69 · #2 01-12-2011, 12:34 PM

Personally I'd go with the 2 separate mufflers rather than the big crossflow...... Better flow and better sound

As for the pipe.... Mandrel bent tube is better since it won't have kinks or wrinkles at the bends. General rule is 2.5 inch pipe will support up to around 500hp no problem.... When you start pushing much over that it's best to go up to 3 inch

If you do a search there are tons of discussions on exhaust size

**CamaroAJ** · #3 01-12-2011, 02:32 PM

with a 468 you might be over 500hp already and should go with 3"

speedjohnston · #4 01-12-2011, 03:08 PM

I wouldn't use the 2 1/2 in your application if your looking to get the most out of your motor. We haven't even had very good luck with flowmaster using them vs same size in another brand. I broke all the baffles out of mine with a 600hp small block and 3" flowmasters, and my buddy picked up 4/10 in the quarter switching to another brand that was quieter under normal driving. Not knocking flowmaster, but thats our experience. If you don't care about getting the most out of your motor and like the sound, then buy the ones you like. IMO you should go 3 inch and find mandrel bent pipes.

SDMAN · #5 01-12-2011, 04:13 PM

Ditto on the 3" and mandrel pipe. A strong 468 can even use 3.5" to the muffler and 3" tailpipes, but either way 2.5" is completely inadequate. I myself cant stand Flows, but thats a personal preference. Go with what pleases your ear.

lukky 71 · #6 01-12-2011, 06:56 PM

I don't mind 3" pipe. I was looking for something that fits well under the car. I don't like mufflers that hang down that's why I was looking at flowmaster that tucks well under the car. I'm openminded. This is a street car what fits the best. I've lowered the car about 2.5" and leveled the back to match front. Were can I find mandrel bent 3" pipes. Thanks for the help I'm going with the 3" pipe now.