225 exhaust advice needed

[4.20]

Hi guys/gals

I've got a delema. I've got a 68 4dr that's got the tower of pwer under the hood. and I've aquired the super six with alm. intake. I need to upgrade exhaust and I'm curious to know how much of a power gain is there with oem manifold v.s. duals. I'm not thinking about any other headwork or cam at this point as I haven't decided to go V8 or not

If duals are used, what size? 2 1/4, and could this be used with a 318or340?

my goal: is to lay some rubber when I drop the hammer, and sound decent

thanks

 

[Twistex]

With the Dutra duals, I've heard reports of between 8-14rwhp. But, it's all very build-dependant, and I have yet to find any rock-solid numbers. A few errant dyno slips here and there, but once again, we're talking very different builds. For rough estimates, hedging your bets on an 8% gain should be safe.

 

[2 Darts]

If you also got the Super 6 exhaust manifold, you have an outlet diameter that will work with a 2.25" pipe.

My Demon 318 with a warm up has duals and my stock /6 73 has a single 2.25" pipe. The 73 uses a generic "turbo" muffler and a PowerPipe SC exhaust manifold. The tone is a little deeper, but still sounds like a /6.