For what you'd spend on an aftermarket system, you'd be better off picking up a 1995 or older jeep (any model) with the 4.0 and swap the engine in. A 4.0 will drop in where that 4.2 is right now. You'll gain 70hp. I suggest the 95 or older models because their OBD-1 EFI engine harness is very easy to reverse engineer and transplant. I did this swap in my 88 YJ Wrangler. Junked the bagged out 258 and dropped in a 99 dakota 5.2 magnum and used a 95 grand cherokee engine harness. I think the weight is about the same or lighter as my front end seems to sit a smidge higher now than it did with the old 258!