Removing a cat is a Federal offense in the US regardless if you have emissions or not and the fines aren't cheap. You will gain hardly anything by removing it, especially on a 3.9 and you can make your exhaust plenty obnoxious while keeping the cat. Straight pipes sound awful on most engines, inlcuding V8s, do everyone a favor and get a good muffler. Any tool can make an exhaust loud, making it sound GOOD is another story.

 

I think exaust going through the hood sound kicks *** especially on V8s, but thats illegal and would bring down the back pressure, but do they have smaller catilac converters, becuase ifs illegal to take them off i need smaller ones because once i do the swap, im going to have each side be on an indevidual pipe that exits between the cab and rear wheels on each side

 

Backpressure is not a good thing. Ask anybody who has ever built a race motor and see how much backpressure they try to get out of the exhaust.... none. The best possible senario is to tune the headers so there is a vacuum at the collector to bring backpressure down to 0 and literally suck the exhaust out of the cylinders.

 

I thought you were supposed to get some back pressure in at least carbed or TBI engines because a while back i was told that if you take the back pressure off you lose power

 

I have heard on a carbbed engine you can burn the exhaust valves without backpressure, but that doesn't mean having backpressure will help the motor, that just means you need to run titanium valves to safely run it without backpressure.

 

But what about the power issue

 

Basically backpressure in the exhaust means the engine has to work harder to push the exhaust out and therefore takes power. Honestly, you'll never notice the power difference in daily driving, but it is there.

 

Then why were people telling me otherwise?

I think this is one of the threads i was talking about with people telling me otherwise
https://dodgeforum.com/forum/1st-gen...87-3-9-v6.html
after reading it it looks like the exaust portion starts at post #5

 

Probably because this will forever be a debated topic, but nothing anybody ever says to me will convince me that backpressure is needed to produce power. I can accept that backpressure is necessary to keep the valves from burning up, but that can be fixed with titanium valves.

 

Oh and you were talking about tuning headers, how do you tune headers? and if you dont need back pressure than would an engine run with the power its supposed to have without manifolds or headers on it?