i recently cut my muffler off and filled it in with exhaust pipe. it sounds good, but i was wondering if im gonna gain or lose by doing this. power or gas mileage gains or losses? anybody else done this to their pickup?

 

My brother put true dual straightpipes (with the stock cats still in place) on his '97 with a 4.6, he gained about 2-3 mpg since his truck wasn't downshifting at the first scent of a hill. I did the same thing with glasspacks on mine with similar results (although quieter) People love to say that it kills your low end power, but our trucks are much more content cruising at 1500 RPM than they were with the stock setup.

 

I find it hard to beleive that you'll gain 3 or even 2mpg with straight pipes.

 

It is amazing what happens when the truck isn't always grabbing third on a hills for no real point, his was really bad at it. This is highway only, for some reason around town got worse.