They're factory ratings, so they don't mean too much, but my Mark VIII is rated at 280, my ETC is rated at 300. IIRC from my time on cadillacowners I would usually see L37 (the 300hp N*) dyno around 235whp - the 4T80e is said to lose about 24%, so that's pretty close. They do have 3.71 gearing and a bit more aggressive first (2.96 vs 2.84,) but they also shift at 6500, and the stall 'seems' even lower (maybe ~300-400rpm) than that of the 4R70w... As for stock vs stock acceleration, the ETC does have an advantage - but if I only cared about stock I wouldn't own a Mark VIII...