this doesnt make sense? the cat is a splitter? why would you run a ypipe after the cat? unless you had a cutout or something?....and 14-15mpg? Are you guessing, thats better than stock unless you mean highway...Of course you never said what engine you have?

I cant believe you guys that remove your muffler and cat dont see a lose of low end torque from loosing most of your back pressure? everything I've both experienced and read says you need the right amount of backpressure for lowend torque, to little or to much will crush power and performance...

 

i have a flowmaster 50 series...that alone produces enough pressure. the y-pipe after the cat im guessing is for duals.

and im talking highway miles...about 10 per gallon

 

but he then said he had A flowmaster he gutted?

curious? do you have a bored out TB and higher flowing manifold to go with the better flowing exhaust and heads? if so I would think you would have a power increase all the way..... maybe you need a tuner as its outside the stock computers tuning capability? just guessing here....

 

The check engine light is from removing the cat itself. I am kinda running the same setup as you AL. Gutted cat, and then I have 2 FM 40's series. I get CEL lights for the cat only when I'm hauling loads, or am diving like a bat outta hell. MPG really wasn't too big of a loss. I see a larger loss running a 180* stat. I did notice a high end torque difference like you are talking about. Nothing major, but enough to set the butt dyno alarm off.

Sounds like you need to throw a magnaflow cat on the system and see what that gets ya...

As for the noise? I can only imagine. I ran a chopped exhaust for about a week myself and would get headaches by the time I got down the road 10 miles from the noise. When it was chopped, I felt like every time I had my foot on the floor, I was making all kinds of noise, but not going anywhere.

 

The cat was already gutted when I got it. I wasn't aware of this until a month or two after I got the truck. It had a flowmaster duals on it when I got it and I had the exhaust shop put a y pipe in place of the flowmaster. Straight highway like the interstate with cruise set at 65 I get 16 mpg's. I live in the country I drive 18 miles one to work with like 6 stops. I get about 14.5 mpg's. When I go to town in constant stop and go I get 13 mpg's. I go to the same gas station same pump and when the pump stops itself I stop. I have ext cab 4x4 5.9 265 75 16 tires and nothing kn drop in filter.

 

loss of back pressure has nothing to do with loosing miles or performance you could have 0 back pressure and the best performance.. but go to big and the exhaust losses velocity and slows down you could run straight all the way back no cat no muff and keep it 2.25 and get very good performance.. plus it would be loud...

 

Many engine wont run without an exhaust....try running you engine without the headers or exhaust manifold...I hear one person say you need it and one say you dont..I know there is other things to consider likw scavanging gases and reversion but bottom line is the exhaust makes a difference....my vw runs like **** when I remove the mufflers....I have more low end with them on.... I'm no expert by any means but I know there is two sides to this coin.

 

alabamaram, i saw your picture of your o2 sensor with non-foulers stacked on it. is that the upstream? you know, the one that controls the a/f ratio.
if it is then that explains your issues. the o2 that controls the a/f ratio is supposed to have its tip in the direct path of the exhaust and the non foulers take it out of the exhaust. put that o2 in the pipe without the non foulers and see what happens. worst case is you get a solid cel saying that the cat is gone.

 

He has a 95, it shouldn't have a downstream O2, so if he does have non-foulers on it, that is the problem.

 

ok, wasn't sure about the downstream deal. but when i saw the non foulers in a picture from another thread, i knew that they would cause problems.