Yes, the R.T. Cat is supposed to be up to 8 HP. I installed the RT Cat (which inludes the downpipe and u-bend removal) and Borla's Cat-back exhaust on my '98 GTP two nights ago...Some people say that you won't feel a difference with an exhaust upgrade such as this, but I definately do. This upgrade increased power significantly by reducing KR, therefor letting the rest of my mods perform closer to their peak performance. I noticed the most increase from about 30-55 MPH and 70+...If I had to estimate, I'd say my RT Cat and exhaust helped add about 15 HP. I wish I would've done a run with my brothers Passport GT2 G-Timer BEFORE I installed it though...oh well, I'll have that info for ya guys soon...
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'98 GTP Coupe - 3.25" Pulley, DHP PCM 1.0, FWI, Thrasher Shift kit, Aux. Tranny Cooler, 160 T-stat, Borla Cat-back exhaust, Random Tech High-flow Cat, 18" Eagle Alloys, F.1 Carbon Fiber Ram Air Hood