I put and exhuast cut out before my cat on a 99 F250? The cat is massive on these trucks and I think that could really free up alot of power. Any ideas?

 

I dont know if you if your running a gas engine or not, but I took the last 2 cat's of my150 w/ a 4.6 and it helped a bunch. probably couldn't hurt.

 

Interesting...me and a few folks I know have gutted the pre-cat, I've not heard of removing the rear ones.

If you have to do it in your area, did you pass smog OK?

 

Because my truck is a new model I am required to run the cat, what i was talking about doing is putting an exhaust cut out behind the cat so I will still pass the test.

 

we dont exactly have any smog tests, but annual inspections are supposed to make sure you cats. the only catch to that is they state your only reqired to have 1 per side/head. since ther are 4 on the truck I took advantage of this.

 

Removing the cat out of the system won't give you anything in the low end of the RPM scale. Torque is all about the velocity of the exhaust flow, not the amount of exhaust flowed. If you remove the cat from the system the truck will breath easier but it will cause the exhaust speed to drop. This causes your torque to drop at the place where you need it (down low) and all the horse power will shift to the higher rpms.

Yes, it will sound mean, but sounding mean and going fast isn't in the cards for a 5500lb truck.

I'd keep the cats, they flow pretty well and will keep the speed of the exhaust up. Start looking for headers they don't make any that I know of yet for the SD, but keep looking new things come out all the time. Exhaust shops may even make you a custom set, but they will be pricey. The headers will help increase your torque a bit because they help with the exhaust velocity as they are all small diameter (1 1/2 or 1 5/8") and designed better than stock and not shaped like a log. Once you're beyond the healthy restriction of the cats then you can open it up... If you had a power adder then you could think about opening it up before the cats, but you don't have a dragster so you shouldn't have a short exhaust.

-Kerry