flowmaster

[spazegun2213]

ok, so i think i should invest in an exhaust... i think, since i can get a flowmaster 40 for $70, how much would pipes be for it? I mean i think I'd need to go to a shop and have them custom bent. Also, whats the diameter comming from the srock cat? I need to keep the cat, well, i need to keep it for inspection once a year. Another question is a highflow cat worth it? and if I'm increasing the diamater of the pipes shouldnt i start with headers as well?

Basicly what i want to know is whats the most cost efficent exhaust upgrade.

thanks

 

[junkjeep]

I think Rusty's has cat bak flowmaster set-ups for under $200, depending on the year of your xj some kits are 2 1/4 and some are 2 1/2. I'm running dynomax on my xj's and the 92 is 2.5 and the 95 is 2.25. Why I don't know, there must be a clearance issue.

 

[Osprey413]

Let's see. There are alot of ways to answer this. I'll start with the cat first because it is easiest. The XJ comes with a catalitic convertic that is practically hi-flow to begin with. It is the honeycomb design and if you look at most aftermarket cats, they too are honeycombs. You really wont get any extra power from changing the cat. The only reason I would ever say to change the cat is if your stock cat has rusted out.

For the headers, you may or may not want to change them. I've heard that the headers are a choke point in the XJ exhaust system due to the fact that the stock headers dont sit right on the exhaust ports. I believe this seems to be worse on the older model XJ's than on the new model XJ's.
For the muffler, dynomax seems to be the best for the 4.0L. You probably wont get much of a horsepower gain from the flowmaster, but it will certainly make alot of noise. Right now I am running a Gibson cat-back system that honostly I am not too impressed with. I just dont think that the XJ has alot to gain from an exhaust modification. I may get burned on that one, but honostly you can only gain so much from a bigger exhaust.

On that note, you need to know that the best (and probably most economical) option for you would be to get the flowmaster with some pipe (shouldn't be too expensive) and then buy an intake of some sort. Rusty's air tube works well. With the combination of intake and exhaust you will get the best results. You can only let out as much exhaust as you take in air. If you have a restrictive stock airbox with alot of exhaust modifications you will only get so far. Not only that, but you could possibly loose horsepower with alot of exhaust mod's if you don't change the intake. If your backpressure gets too low, the power will drop. If you wan't to test this take off your muffler and drive with just the cat, you will notice a severe drop in power due to the loss of back pressure (although it sounds bad a$$ without a muffler).
Once again, some of you engine guru's may burn me on this, but from what I have seen and heard about I would say get the flowmaster then spend the money on an intake instead of a cat and header.

 

[Atl XJ]

I'd also recommend geting a new Y pipe. The stock one is very restrictive with that kink in it.

FWIW, I have a Flowmaster 50 series deltaflow with a high flow cat (my stock one took a dump) and 2.25" pipes and it sounds great. Nice sound without being too intrusive. Next will be a new header and Y pipe.

 

[spazegun2213]

hmm, Y pipe... i donno that i want to go THAT far on my xj. I have a TBS and will be getting the right intake in a week or so. I'll also have the stock TB milled to 60mm (to take out the bevel) and I was thinking of bying rebuild heads and porting them, but I think that may be a little much for me. So Exhaust is the next logical bang for the buck point.

I mean my jeep is already loud, so getting louder is not the objective. Ok, so I think a set of pipes and a 40 might be the next step. I just want to know what size 40 to buy (if I'm going to by it) so the pipe fits perfectly.

 

[Osprey413]

got a tape measure?

 

[Ramsey]

i am running mufflerless and want to add one, will a cheap glasspack, cherry bomb, add to backpressure that was lost due to removing the muff? i hope so since i have access to a free one

 

[spazegun2213]

tape measure?

 

[Dr. Dyno]

ok, so i think i should invest in an exhaust... i think, since i can get a flowmaster 40 for $70, how much would pipes be for it? I mean i think I'd need to go to a shop and have them custom bent. Also, whats the diameter comming from the srock cat? I need to keep the cat, well, i need to keep it for inspection once a year. Another question is a highflow cat worth it? and if I'm increasing the diamater of the pipes shouldnt i start with headers as well?
Basicly what i want to know is whats the most cost efficent exhaust upgrade.
thanks

Rusty's Flowmaster cat-back is as good as it gets and is tough as nails. I'd also go for the high-flow cat since that also adds a couple of ponies.
The Dynomax cat-back is a good cheap alternative but its muffler isn't as tough as Flowmaster's.
The downpipe from exhaust manifold to cat is very restrictive. You could go the whole hog and replace the manifold and pipe with a Borla header (it comes with its own downpipe, and it's a good excuse to replace the crack-prone stock manifold). If you don't want to spend the extra money on a header, you could just ask your muffler shop to make you a better downpipe without all the kinks.

 

[junkjeep]

I'm running the dynomax welded ultra flow on the xj's. I would spend the extra money and up grade from the super turbo. I think the weld ultras sound better not to mention are stronger and flow better. I paid about 175 for the muffler, tail pipe, clamps and adapter at the local bumper to bumper. I couldn't find it any cheaper online. Like I said in the previous post the Rusty's kit looks like a good deal.

 

[jfw432]

I really prefer the magnaflow mufflers myself. I'm pretty sure they're much like the Ultraflo welded mufflers from dynomax that junkjeep was talking about. You can get a magnaflow on ebay for around $50-$60 (buy it now) through a couple different guys. I bought mine from "performance-curve" or something like that. I just didn't like the way the flowmasters sound on a jeep. It's got the sound pattern of a big V8 but the sound is too wimpy and almost like a car where the muffler is about to fall off. Magnaflow is a real beast of a muffler. Weighs a good bit and has huge welds on it. It sounds smooth and still gives a deep sound. It's a straight through design so there won't be any restrictions to it.

As much as I respect Dyno's experience and knowledge I have to go against him on this one. The high flow cat didn't help me one bit. It'll give you more power at the top of your rpm's but if you're like me and barely take it over 3000 then you'll never know the difference (at least on a regular 4.0).

The new down pipe from header to cat will help you because that thing is incredibly restrictive. Headers are pretty expensive and you might as well do the cheapest things first before dropping a ton of money on headers.

 

[Dr. Dyno]

I like the Magnaflow muffler and I have a 2.5" stainless steel unit on my Jeep. It's a very high quality piece.
Regarding the high-flow cat, I did say you'd gain a couple of ponies but, of course, you're not going to feel an extra 2hp by the SOTP.