Thats cool...what muffler are you think about?
I'm sure there's a pulley out there somewhere....lol...let the search begin..I have thought about one myself too...just haven't looked yet..
Well...as far as rims go...you can get any newer Grand Cherokee, Commander, and the JK Wrangler's wheels to fit on your WJ...there are lotsa options...and on eBay....you can find some nice, low priced wheels and tire packages...sometimes even on here...I sold my 17" Overland Platinum wheels with Toyo Proxes Tires to a member for a really good deal...
Here's the choices you have:
WK Grand Cherokee Wheels:
XK Commander Wheels: