well im pretty sure im going to get my cat changed out, and i was going to go with a hi-flow cat, but....as of now im running a single 3" pipe from the stock converter all the way back, so my question is, if i go to a hi-flow with a single 3" pipe will i have so much flow that my back pressure loss would just be ridiculous?

 

Yes, that much is little too much for street driving. All that space compared to the factory pipes will slow down the flow of the exhaust because it lets the gases cool and slow down. Hot gases flow faster than cooler gases. Now if you ever ran your truck at high rpms you would utilize that extra space more effectively. You would be better off getting a high-flow catalytic converter that flows more (than stock) but is remotely the same size as the factory pipe if possible.

The computer won't be able to tune enough to make up for the increased exhaust scavening probably.

 

You didn't mention anything about a muffler, are we to assume your gonna go straight pipe all the way out ? If so, most high flow cats, are in the 2- 2.5" size range. Depending on where your gonna put the tail pipe. you could run say 2.5 into a 3" tailpipe. For low end you need a little backpressure, if you go 3" all the way out and no muffler, yeah your gonna lose bottom end. 2.5" may be slightly better.

 

there is a few people on there that run that set up... i alway hear that,, that is the best setup single 3in..... aim,, d ram,, jason... that all i can think right now that has 3in


but your truck is a 01 you have 3in right now stock, going to high flow i dont think you going to lose it.........

just my 2cent and dont hold to 2 me