[RaccoonJoe]

Figured I would post this here, as well in the tech section. Maybe you street performance guys can help me out a bit....

Working on an '89 XJ, 4.0L, AW4, 225K+ miles, etc. I lost the exhaust the other day, and am now driving around with just half a muffler. I was shopping for replacements, and found a couple of questions.

Will I see any improvement by going to a 2.5" exhaust, from the front of the cat back?? (cat will either be removed or replaced with hi-flow version, not sure yet). This is currently a stock motor, but I'm looking at a CAI (through one of my hood vents) and bored TB in the near future.

Not looking to make a drag machine out of this old girl, but she does see an awful lot of miles. I would just like to make her quiet again, and maybe squeak another MPG or two out of it.....

[JoJo97XJ]

CANT go wrong with Dynomax, it was like $125 from summit when i bought mine. you can kinda hear it on my video

[urban-yan]

performance mufflers don't add horsepower, they free-up horsepower.

Although I'm not 100% sure what you'd get from a FULL 2.5 upgrade, I can tell you magnaflow claims a 6hp/ 7ft/lbs increase on their 2.5" catback.... and that's not a full 2.5" system since it attaches itself to your stock 2.25" cat. I imagine Dynomax would yield the same numbers. oh... and for the love of god, DON'T REMOVE YOUR CAT... just replace/ upgrade it if it's old


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[red96jeep]

yeah i'd say get the dynomax with a high flow cat. then if your daring get some headers and a down pipe.