yea those performance upgrades are all pretty worthless and will get you no where near a 4.0's power, ive got borla headers on my 2.5, maybe pushed a 10 horses outa it and my cold air maybe, maaaaaybeeeeee 3 ponies, my buddy said the 4.0 tb did make a bit of a difference but the tb spacer is the biggest load of crap out today, its the jezebel of the auto mail order catalog