the old 01 exhaust questions

Alright guys i have been searching for a lil while now on the exhaust question/pain for the 2001 xjs. i want to do a complete system replace the old crap and see if i cant get a lil better mpg and sound.

I found a set of headers i like the jba cat4ward, (expensive i know but i have used jba before and loved the resualt) heres a link i found from searching..
http://www.rjroffroad.com/jba-cat4w...-cherokee-40l-offroad-c-577-p-1-pr-17014.html

I was wondering if anyone has used these before and had any thing good or bad to say. or had any other options for headers.

after the headers there are those stupid cats that just should be cut off in my opinion, but the gov. says other wise. I was wondering if anyone has ever installed highflows and if so were did you get them from?

And then from there on out i want to get a kit for the rest of the exhaust i would like to stay jba but cant find any part listing for a 2001, if anyone knows if these are even offered and were i can get them that would be great. if not let me no what your running on your 01 and how you like it.

You might try cross posting this, or have the mods move it to the mod tech, or street & performance forum. No info on replacement pre-cats, but you might want to look at the collector/down pipe just behind the pre-cats. On the older(single manifold) 4.0s, there was a hell of a kink in the pipe to prevent the suspension from hitting at full flex. Not sure if it's still there on the 2-manifold setup If you spend most of your time on highway, and haven't removed the sway bars, you can put a full diameter pipe there and remove some restriction.
I am the wrong person to ask about "better" sounding mufflers. My idea of a great muffler is one I can't hear. The folks around here seem to like the 50 series Flowmasters though.

I wonder if you could just use an older header/downpipe setup and do away with those precats? It's too bad if the jba is the only option, cause those primaries aren't long, nor equal length(but I guess it has to be that way to keep the precats). A borla costs $200 more than that. . .

My 2000 doesn't have pre-cats. I though only the CA emissions models had precats. Is yours CA equipped? The pre 2000 headers have bigger ports. The exhaust ports were made smaller on the 0331 heads, but it seems like the header should still seal up.

You got the good one. It'd be interesting to run the two different 2Ks side-by-side to see the performance and mpg differences. So you have one upstream o2 in the header and one downstream o2 in the cat? Are there aftermarket headers specifically for your setup or is it the same(just header, no downpipe options)?

I think the headers are the same. I've never really searched for a replacement header because I have a '98 head I need to swap in to get rid of my cracked 0331. My upstream sensor is in the downpipe, not the header. It would be very interesting to compare the performance, as I have also seen threads about people wanting to get away from the CA system in areas where it is not required. I know that any time I have got any type of a power tool (chainsaw, etc.) that was CA approved, I had to break off the carburetor adjustment limiters to get it to run worth a shit.

alright thanks guys for the info, i no it has only taken me like 5 days to get back on here its been rough at work.

i guess as far as a final question i would just like to know what kind of cat back systems there are out there and what some of you guys have used and liked...quality and durability are big.