The transmission on the Jeep (SRT8) is good to around 600HP. At that point I had to upgrade it. The carrier and axles never gave me a problem even when I was racing it and pushing close to 800HP.
As for the comment "Nice cars but I still think a sportscar should beat a jeep. ", you can think what you want, but if you're stock I advise you to keep your distance unless you find one on the highway. Keep in mind, Chrysler doesn't just hand out the SRT badge for ***** and giggles.
Stock the Jeeps run low 13's, but you don't see many stock ones. At a stoplight it will appear much faster due to the neck snapping launch that usually puts a bus length on just about anything. After that you would start reeling it in, but at that point the race is over.