I agree RVG.The artical shows them replacing an aftermarket muffler not the OEM.(and the dipshit is doing a burn out in the dirt like it's really cool)I dont trust anything these rags have to say.And non of these aftermarket companys will guarrenty any gains.

 

Yeah but that was when they went from a Flowmaster to a Magnaflow too. Flowmaster = low CFM flow.

Hell they got 5 rwhp from an open filter...that sounds about right to me. The HPP3 gained about 20rwhp seems iffy though. But hell that can depend on how little timing the 6.0 has stock vs how much the HPP3 puts in, if the 160* mode was used, etc.

Well for your truck, do you still have a stock catback? How wild of a cam are you planning to go with?

Eitherway, 2.5" pipes into a 3.5" pipe will flow enough for a mild cam and heads combo...hell probably up to 350-375rwhp. But if you are hell bent on true duals, 2.5" piping will flow fine into an X-pipe with dual mufflers OR you could run a Magnaflow that has a built in X crossover to save some cash.

Cutouts = lots of noise (never said that was bad! ) but loss of lowend power. The gaskets also go bad after a while and need to be replaced. I see them as novelty purposes on a street vehicle where backpressure is needed on an N/A ride to aid in off idle torque. It would not be too bad on a N/A vehicle with a high stall converter, around 2800rpms+, so you won't miss that torque on a WOT run.

 

Cutouts don't hurt your lowend power if they are located far enough downstream.I run custom 21/2 head pipes mandril bent head pipes into a Flowmaster venturi wye,then my cutout with electric opemer.I've never noticed any loss of lowend power,just the opposite I gain power through out the entire rev range.But the supercharger may like less backpressure.

 

Whitt, you got it right. FI likes the least amount of backpressure...hence why you gain power via an open cutout on your Radix. Think like turbos...those get a 4" exhaust!

Now, if I had a small V8 that would wrap up to 7000rpms+ then cutouts would help there.

I figure a freeflow exhaust with a good set of headers, proper sized piping, and straight through mufflers will perform better in all aspects of the powerband (on a street vehicle) vs a stock exhaust with just a cutout or headers and a cutout.