What is the actual difference in magnaflow, flowmaster, roush or really any exhuast performance wise. Are there more power gains with some or what?

 

Flowmaster and other chambered style mufflers and you lose some low end. Magnaflow and straight through mufflers get rid of some of the back-pressure and adds a little bit. Whether you feel it or not depends on how modded you are.

 

Straight through mufflers sound more clear throughout the low and high RPM range rather than chambered mufflers which only sound good when you slam on the gas and has annoying high drone. Magnaflow is the best bang for your buck, but it all depends on what sound your looking for.

 

Dont go Flowmaster, sure they sound awesome, but its not worth the loss of power.

 

I put a 2.5" SI/DO 40 series flowmaster and im regretting it, very noticable loss in low end. As soon as i get a few more bucks im gonna go to long tube headers and true duals with x pipe and 14" magnaflows

 

i have si/do super44 on my truck, and cant notice a difference in my low end
i wouldnt care anyways i love the sound of it!

 

Another benefit of a straight-through design is nice little bump in mpg (once you manage to keep your foot out the peddle just to hear the sounds.. lol).

I gained 1.8 mpg highway just by putting on a Borla SI/SO.. I'm sure Magnaflows, Corsa, etc. help the same..