Originally Posted by bulldog x6
it will be noticably slower but not as much as if you came from an n54 powered E9X
When both are tuned, N54 makes considerably more power than the N55. N55 is slightly better on fuel economy and is cheaper to manufacture. With ONLY a JB4 tune and DCI (costing me a grand total of $600), I'm at over 400 rwhp when I run a 60/40 premium/e85 mix.