New exhaust piping really important?

[jbassxj]

Ok, it seems as if I've been pestering the jeepforum w/ exhaust questions that have been coming up left and right, except I already know the answers I'll get, but I always just hoped for something different.

I gotta cracked exhaust manifold, my gibson headers should be coming in shortly, now I would really just like to finish it out w/ a muffler and a cat.

The only piece of the puzzle that I am missing if I were to get new piping from the cat-back is a downpipe from the headers to the cat, which I guess I'd have to get at a shop, which would cost some amount of money I'm not entirely too sure of yet.

In your honest opinion, how important is changing out piping in the overall value and performance of exhaust modification?

 

[aparke4]

pipe diameter...for that downtube (does gibson supply?)it requires a flange for the header to downpipe connection and there needes to be a bend for the transmission (transmission right?) so that might need to be made and copied (bring original to shop) by any muffler guys... as far as performace (do a search) 2.5 seems to be the best choice for tubing and for off road performance someone that can tuck the pipes up and in close to the body...i had a guy do an awesome job when i had my flowmaster 40 series and random technologies cat (2.5 in and 2.5 out)...make sure if you use your jeep as a DD that you make sure the heat shields are properly in place...the I6 really does well to a freeflow exhaust but i do not recommend taking of the cat. oh yeah make sure that everything is fully welded...the bands and bolt on stuff should be for temporary fixes...umm yeah make sure the bends are as close to the body but gentle as well...the person who installs the pipes makes all the difference...are you doing them yourself??

 

[jeepcherokee95]

What is the most free flowing cat out there now? where can I find it and how much does it cost?


Thanks,

JC95

 

[jbassxj]

pipe diameter...for that downtube (does gibson supply?)it requires a flange for the header to downpipe connection and there needes to be a bend for the transmission (transmission right?) so that might need to be made and copied (bring original to shop) by any muffler guys... as far as performace (do a search) 2.5 seems to be the best choice for tubing and for off road performance someone that can tuck the pipes up and in close to the body...i had a guy do an awesome job when i had my flowmaster 40 series and random technologies cat (2.5 in and 2.5 out)...make sure if you use your jeep as a DD that you make sure the heat shields are properly in place...the I6 really does well to a freeflow exhaust but i do not recommend taking of the cat. oh yeah make sure that everything is fully welded...the bands and bolt on stuff should be for temporary fixes...umm yeah make sure the bends are as close to the body but gentle as well...the person who installs the pipes makes all the difference...are you doing them yourself??

I wasn't planning doing it myself no. I was just wondering how much of a difference getting all new tubing along w/ new header, cat, and muffler makes as opposed to just leaving the stock tubing on there and have the new headers, cat, and muffler. I do appreciate the info you gave though! thanks

 

[jbassxj]

I know I have a feeling I'm asking a lot, but I honestly don't think new tubing makes that much of a difference in the overall performance. I was just seeing if someone actually knew but I guess not. Oh well, thanks for the info anyway if you have anything to add.

 

[CW]

If you look at your stock down pipe you will notice that the factoty included some crush bends that don't flow well at all, so a good 2.25" down tube with good bends makes a difference. High flow cats are available on ebay for a decent price. And a 2.5" cat back with mandrel bends makes a big difference. If you haven't yet, I would check out Rusty's cat back it is a really good deal.

 

[lilredwagn]

I obviously can't speak for anyone else's experience (or yours - as I have a Mike Leach header), but all my performance gain came from my header - I noticed a 1 second drop on 0-60 while it was still plumbed through the stock exhaust. After putting on 2.5", a magnaflow, and high flow cat, there was no further increase (except in noise )

 

[jbassxj]

thanks for all the replies guys

I just got through doin' the install sat and here's what I broke down and purchased:

won a good bid on gibson chrome headers

got rusty's flowmaster 50 catback

magnaflow cat

Only thing not installed is the cat, and I need to see how much it'll cost me to get a new downpipe and cat installed. Also, my friend decided to buy some header wrap for me so that was installed and the hood temp. has decreased severly (in a very good way).

When I go back and re-tighten the bolts on the header and inspect everything, then I'll wail on her and see what gains I've really received.

(I've already done a lil' wailin' and it's pretty nice, but I haven't done balls to the wall wailin' cuz I just don't want anything breaking on me)

W/ all that being said, the flowmaster 50 has a beautiful sound at idle, once past 2K rpm it sounds whateva (to me) but it's still nice. Of course not everything is done so all of that is due to change.

I do thank all for the help. My main goal was to save a buck or two in trying to do a repair/upgrade and I think I succeeded fairly well so far.

 

[MrShoeBoy]

I noticed a huge difference between the stock down pipe and a new mandral bent 2.5" down pipe. I think the advantages of the bigger down pipe are more apparent on a stroker motor than on a stock 4.0L. I cant really comment on a high flow cat since my high flow cat died a few weeks ago. I ended up removing the pieces inside to it wouldnt rattle and plan to run it as is. Most of the pieces ended up inside my flowmaster so it was cut open and the pieces removed along with a baffle that fell out as well. So a new muffler is soon to be ordered and installed. Anybody run a Spin Tech brand muffler? I want something different than the flowmaster since everybody and their brother has one.

AARON