Stock for stock, Jeep SRT8 owns the TBSS.
SRT8s accept upgrades very well, that’s not unique to the LSx line.
Although the SS wins the comparison contest:
Without question, the Jeep is the hottest rod here. Although the two have fairly similar power-to-weight ratios (11.4 pounds per horsepower for the Jeep, 12.3 for the Chevy), the Jeep easily outruns the SS.
http://www.caranddriver.com/comparisons/10848/2006-jeep-grand-cherokee-srt8.html