I'm about to replace the stock single exhaust system on my 69 350 with headers/ duals. I've got Holley 1 5/8" x 3" headers. Any opinions on Summit 2 1/4" system ($129) vs. Jegs 2 1/2" system ($159) to finish out the exhaust?

This is a stock 350 block at 9.6:1 CR, .454" and 218 degree cam, 600 cfm carb, bone stock TH350, 2.56 rear end.

Is 2 1/4" big enough? What if I do the 383 conversion, or put shorter gears (3.42-3.73)in the rear, how does that affect the decision?

thanks!

It does affect it. I would go 2.5" to allow yourself some room to build into. 2.25" is for stock/stock.

I think dual 2 1/4 pipes on a lower comp small cammed 350 is fine. When I had similar engines I used 2" pipes! I think if you gonna sauce it up for more hp, or change to a 383, you'll likely want 2 1/2" pipes though.

Any dual exhaust is going to be an improvement over the 1 7/8 single exhaust that's likely under the car now.

I figure that anything worth doing is worth over-doing, so I'd be looking at 2 1/2 pipes and an "X" crossover. I have a 2 1/2 Flowmaster Force II on my 'Camino now, and like it a lot...but I'd use an X if I was doing it again.

If you are starting from scratch go 2.5". There is no reason to go smaller than that -- larger exhaust pipe won't kill low end TQ that's an old wives tale. Mandrell bent pipes will help too.

Larger pipes will make your exhaust a little louder though and a little harder to fit --especially when you start getting bigger than 2.5".