I had borla's stainless headers on my 4.0 TJ and certainly felt an improvement. My stocker had a crack in it so it was a need more than a want. It was not cheap, but it was a quality piece. Coupled with a borla cat-back and a random technologies performance cat, it had a great sound and 100% stainless, so I knew I'd never have to replace. All of borla's stuff has a million mile warranty I think. I have also heard good things about thorley headers, but I have no experience with them.
Tony-13 JKU Sahara, Black. LED white fender lights & signals, JW Speaker LED heads and fogs and tails, LED windshield and rear bumper lights, retrofit Homelink GD opener, LED interior lighting, shorty antenna, weathertech liners, Drake gas filler. 67 Designs phone mount, Rugged Ridge hood catches, dead pedal, ventshades, rampage windshield tie down & stops, solid stainless lugs, 20% front tint, sill guards, FMF spare delete kit, OffRoadHeros cargo top, K&N FIPK intake, Smittybilt Molle roll bar covers, and lots of carbon fiber hydrographics. ToDo list: programmer, exhaust, and a bunch of other stuff.
15 Cherokee KL Latitude Edition with cold weather package. Bone stock.
PAST JEEPS : 99 TJ Sport, 98 XJ Sport, 04 WJ Limited, 06 WK Laredo, 09 KK Liberty