Exhaust Question

[FastFocus]

Hey all, ok i know i've been asking a ton of questions, but so far everyone has been a great help. this is my last one for a bit.

The stock exhaust is 3.5" i'm looking for an exhaust for better MPG. I was looking at the 5" exhaust(for sound and mpg's) but i've been told i dont need it til 500hp, which i'm not going after for a while(at least till warranty is up). So then i started looking at 4" exhaust. I know i need the stock cat to keep my warranty. so a 4" turbo back MBRP with keeping the stock cat is $380.
my question is this. Instead of paying close to $400 for exhaust. Can i gut the cat to keep the Cat appearance, and replace the muffler with a straight through muffler since the stock pipe is only .5" less than the 4" aftermarket and get almost the same MPG's?
i don't see how .5" is going to be that big of a deal, but i could be wrong. thanks,

[Raul@Stealth Automotive]

Originally Posted by FastFocus

Hey all, ok i know i've been asking a ton of questions, but so far everyone has been a great help. this is my last one for a bit.

The stock exhaust is 3.5" i'm looking for an exhaust for better MPG. I was looking at the 5" exhaust(for sound and mpg's) but i've been told i dont need it til 500hp, which i'm not going after for a while(at least till warranty is up). So then i started looking at 4" exhaust. I know i need the stock cat to keep my warranty. so a 4" turbo back MBRP with keeping the stock cat is $380.
my question is this. Instead of paying close to $400 for exhaust. Can i gut the cat to keep the Cat appearance, and replace the muffler with a straight through muffler since the stock pipe is only .5" less than the 4" aftermarket and get almost the same MPG's?
i don't see how .5" is going to be that big of a deal, but i could be wrong. thanks,

just take off the muff..... you can gut the cat...

you will not really see any diff in MPG though.. even if you went with a 4" kit...

their are a lot of things that determine MPG.. thinks like:
Tire pressure
Clean filters
your right foot
then tuning, and flow

a larger 4" exhaust is only meant for a lil better flow and to get those EGT's down lower once your tuned....

[FastFocus]

well i'd like to put a straight through muffler on it, i don't really wanna hear the turbo wine THAT loud. what do you recommend for a straight through muffler.

also, i've heard that an intake, box and chip will improve mpg's and really open these trucks up. is that not true?

[Raul@Stealth Automotive]

Originally Posted by FastFocus

well i'd like to put a straight through muffler on it, i don't really wanna hear the turbo wine THAT loud. what do you recommend for a straight through muffler.

also, i've heard that an intake, box and chip will improve mpg's and really open these trucks up. is that not true?

im not sure of anyone that makes a straight through muff for a stock exhaust.. their are plenty that make it for a 4" though...

your stock intake will flow more than enough air to support over 400hp.. so you dont need an intake.....

if you really want better MPG then you need to install a tuner... and gauges...

i recommend a custom tuned SCT.. it is the best for the 6.0L