I can only speak based on my own experience, and I have noticed a decent boost on my 4.4i. If anything, Dinan is pretty conservative with their performance numbers and they won't put out a number until they consistently reproduce it on a dyno. They also point out that software alone will NOT give any hp gain without the corresponsing hardware mods. Anyway, for the 4.8is, it looks like you'll get 15 hp for the CAI and 9 hp for the throttle body. Throw in a free flow exhaust and you've got another 8 hp. That's 32 hp total. Most of that "bonus" is hidden until you floor it past 5000 rpm. Anyway, I was not disappointed. The other reason I went with Dinan is that they're fully approved by BMW NA. No voiding of the warranty, or having to reverse mods when you take it in for service.

F18: Carrier aviation fan