Straight Exhaust Pipes -Are they bad?

[237TCE66]

Hi All,

I wish to change the stock exhaust pipe with silencer to a straight one on my 1983 W-350 with 5.9 ltr 4 bbl engine. It has no catalytic converter.

Here in Zimbabwe (Southern Africa) -where I currently live, high-tech exhaust systems are not available.

If I go for a simple straight pipe/s will it negatively affect the fuel consumption? Will I get increased power?

Your advice will be very helpful!

Cheers!

[B-300]

I would go to duals or at least redo the Y-pipe were the front pipes merge as this is a choke point.
You won't gain much be going to open exhaust (other than noise)except at high RPM.
As to mileage reasonable pipe sizing is what matters the most: 2 to 2-1/4" for duals or 2-1/2" for single pipe. If you do a bunch of mods then you could go to a larger pipe but would need headers also.

[Speed Dragon]

It won't hurt anything, mileage may go up 1-2 mpg over a stock muffler. It will be pretty loud though, and probably won't sound too good (lots of popping and banging on deceleration ;)). I'd run at least a glasspack on it, if it was me I'd want a chambered muffler of some sort (Flowmaster, Thrush, Dynomax, Flowtech etc).

If you are keeping the single exhaust, I'd upgrade the y-pipe as mentioned. You can buy nice y-pipes on Ebay. I'd run 2.25" pipe down from the manifolds and into the y-pipe, then 2.5" on the single outlet pipe, w/ a 2.5" muffler. The main thing for good flow it to keep the bends as smooth and wide as possible. Sharp 90 degree bends don't flow well, particularly when made by a crimp bender (pipe crinkles on the inside or the bend). If you can replace a 90 w/ 2 45 degree bends, it will help flow. Or if you can make the 90 bend w/ a larger radius.