when I was taking welding classes about 9 years ago I learned something long known in the pipe industry- "double the diameter (I.D.) and you quadruple the flow capability". Now, having brought that to light, I'll enlighten you a bit more, on a NON- mass air flow sensor controled or NON O2 sensored intake/exhaust system, i.e.- a normal carbed engine w/ no electronic fuel dilivery - our jeep/amc engines in other words, YOU CANNOT HURT PERFORMANCE BY PUTTING ON A LARGER I.D. EXHAUST PIPE. the same is not true for the o2 sensored/ mass air flow sensored engine. On OUR engines, If you want to run 8" pipe, it wont hurt a thing. if you run .75" pipe...it will hurt your performance.
Another point: As far as "fast moving exhaust gasses" goes, it makes no difference how fast the gasses are moving, as long as there is a small or preferably zero level of BACK PRESSURE. back pressure is caused by a restrictive muffler, cat, pipe, manifold, even a high pressure tail pipe exit, as in, the exit end of the exhaust pipe being in a high air flow area of the vehicle, hampering efficient exiting of exhaust gasses. for an extreme example, think about driving 70 mph with your exhaust pipe facing out the front of your wag! dumb example, wouldn't happen in the real world, but its just an example.
Now bearing in mind that an engine is an air pump, and the freer it can move air in and out of itself the more efficient and thus more powerful it will be, the largest diameter, and shortest running exhaust you can install is undoubtedly the best. of course, there are monetary, legal and spacial concerns as to how big you can go and still be practical.
With all that being said, I'd go with a good 2.5" or 3" free flowing system, duals or single. the duals and headers really only show a marked improvement at higher rpm, say free way speeds. so find out what you are going to be doing and go from there. as far as my preference sound wise, I'd stay away from glasspacks unless you want LOUD! but that's just my opinion. Matt W.
A.K.A. - Mr. Tinkerjeep.
Another point: As far as "fast moving exhaust gasses" goes, it makes no difference how fast the gasses are moving, as long as there is a small or preferably zero level of BACK PRESSURE. back pressure is caused by a restrictive muffler, cat, pipe, manifold, even a high pressure tail pipe exit, as in, the exit end of the exhaust pipe being in a high air flow area of the vehicle, hampering efficient exiting of exhaust gasses. for an extreme example, think about driving 70 mph with your exhaust pipe facing out the front of your wag! dumb example, wouldn't happen in the real world, but its just an example.
Now bearing in mind that an engine is an air pump, and the freer it can move air in and out of itself the more efficient and thus more powerful it will be, the largest diameter, and shortest running exhaust you can install is undoubtedly the best. of course, there are monetary, legal and spacial concerns as to how big you can go and still be practical.
With all that being said, I'd go with a good 2.5" or 3" free flowing system, duals or single. the duals and headers really only show a marked improvement at higher rpm, say free way speeds. so find out what you are going to be doing and go from there. as far as my preference sound wise, I'd stay away from glasspacks unless you want LOUD! but that's just my opinion. Matt W.
A.K.A. - Mr. Tinkerjeep.
Comment