I'm going to be putting a new exhaust system on my Chevelle this week. The engine is a 350, pushing probably close to about 260 horsepower maybe. Right now the setup are headers (unsure of collector size) into individual straight pipes, to glasspacks then dumping right after the axle, but so they ends of the pipe aren't visible. I'm wanting to go to an X-pipe with Hooker Aero Chambers, and end it with the chrome SS exhaust tips. What would be the optimal pipe size be for this? I'm about to put a Q-jet on (currently 2-bbl) which will boost the HP some, and in the future want to put good heads on, with a goal of at least 350 horses if I'm lucky, so around what exhaust size could accomadate this range? Glasspacks are fairly restrictive, so am I looking at an HP gain with the new setup, even if like 5 HP?

On the same note, I'm wanting to bid on some mufflers from eBay, assuming there is no damage to them. Here's part of the description for the dimensions: "They are part number 21505. 4 3/4 in. x 10 1/4 in., 3 in. offset inlet/center outlet, 14 in. case length. They have 3" 3 bolt Header flanges welded to the Inlets & Outlets. They also have short 3" diameter tailpipes with heavy duty rubber hangers."

Will I be able to adapt this to the right pipe size, or are the inlets/outlets too big for what I'm needing? And since they're already welded will that not work? Can't the exhaust shop just saw off and re-weld or whatever they need to do?

Thanks for your help, I can't wait to get my new system on.

A set of headers with a 1-5/8" primary about 39" long with a 2-1/2" merge collector about 15-20" long will add considerably to your power curve. Put your 2-1/2" x-pipe at the end of the collector. Downstream of that 2-1/2" pipe with 2-1/2" mufflers will be plenty.

That's good news about the power curve, thanks. Hopefully I can feel a boost when I floor it rather than hearing from the exhaust what sounds like my engine exploding.