Originally Posted by TMack
Thanks James. My biggest concern is that I've read in a couple of places that the '06 330i's were so well maxed by BMW people were actually LOSING performance when messing with intakes, exhaust, etc. What's you experience with 330i's?
Well lets use the intake as an example--you can definitely lose performance, and I'm sure you understand that, but the reason why one might LOSE performance instead of gain with the intake is because they might not have a properly shielded intake. A properly shielded intake shields the intake of air of under-hood heat. You need the coldest air you can get to see power gains. And an intake that's not properly covered might do a worse job of filtering out dirt than the factory air boxes, causing a not-so-efficient intake.
Cold air is great, this is why there are CAI (Cold-Air Intakes), but people don't like the risk of sucking in water during wet seasons, which is definitely not good news...
Other than that, intakes generally help with the throttle response and has some power gains to provide for you. Looking at the Gruppe M intake, you can tell that is well covered, and it will suck in a good portion of air in through the grill. Don't expect a power-loss with that intake
Just make sure when you're getting exhaust/intake systems, they're quality systems.. You want to make sure the piping doesn't leak or fall apart as time passes. The pictures/links I gave you are of high quality, and it is sure to give you some power that you're looking for.