Factory Exhaust Restriction

[jbain]

I have a 98 XJ with a Poor Man's 4.6 it has a stock head, 62mm TB, 24# injectors and a 99+ intake. The only thing I've done to the exhaust is to upgrade the CAT and install a Flowmaster. My question is does the factory restriction at the Exhaust Manifold really make a difference to my performance or should I spend the money to put in a new pipe. Also I have a factory 2000 Exhaust Manifold (without the CATS, it just has two long downpipes) and was wondering if this would be an upgrade to my factory manifold? It calls for a different gasket so I'm hesitant to use it even though my old one is cracked just because the ports might be a little different. Any help would be greatly appreciated.

[Cheromaniac]

I suggest you keep the existing '98 factory header and just upsize the downpipe plus the rest of the exhaust to 2.5" piping.

[jbain]

Thanks for the response Cheromaniac.... I'll start researching available aftermarket kits.

[Muad'Dib]

Id recommend going to a local exhaust shop that does mandrel bends and have them do it. You would be hard pressed to find a "kit".

[Cheromaniac]

Id recommend going to a local exhaust shop that does mandrel bends and have them do it. You would be hard pressed to find a "kit".

x2.

[woodjeep]

I had mine done at an exhaust shop several years ago. They mandrel bent the downpipe to fit my 2.5 catback. I had given them the catback system..they made the downpipe and welded it all together for around 200 bucks...only thing is the guy said that he could not match up a 2.5 downpipe with the then..stock exhaust manifold..it would have been too big a dia and not mated properly. He had to make the downpipe out of 2 1/4 pipe...its probably just as good..no issues

[jbain]

Thanks guy's.... I really appreciate the suggestions.