Originally Posted by GWitha135i
1. What companies are currently doing tunes for the N54, and the N55?
2. What is the best tune? (I know, loaded question)
3. Is the BMW Performance Tune, currently available for the N54, not the N55 really a cost effective option?
BMW Performance Power Kit (For Vehicles with M Bumper) $1,861.98 on the BMW Website
4. What are the differences in performance, sound, and cost for the different kinds of exhaust (axle back, turbo back, etc...)?
if you would like to dismiss this that's fine, but I have looked at this site enough to know these are common questions. It would be nice to make this a sticky and really get common questions/answers posted.
I do not envy the person that intends to keep this up to date
1. burger motorsports (jb3), vishnu (procede v4), GIAC (stages 1-2+), cp-e (standback), a few other flash companies
2. i've used the jb+, jb3 18ohm, and now i'm running a procede v4. i'm happiest with the procede, it's so much smoother and includes tons of extra features. vishnu is about to release a naturally aspirated map for the v4, should you want better gas mileage on a long trip or commute. the v4 also is far more advanced than the jb3 and i'd argue it's safer. i think the best 2 tunes currently are the vishnu and GIAC. the cp-e standback is awesome, it allows custom tuning, which allows turbo swaps, fine tuning of afr/timing/etc. i think in the coming months/year or so, the standback will gain popularity as ar design is running this tune on their single turbo swapped n54.
3. bmw power kit is basically a very mild tune with much better cooling components. i don't think it's worth the money, but everyone's different
4. axle backs provide great sound, the true performance potential is realized in catless downpipes and catless midpipes. dp-back exhaust will yield the second most power exhaust wise, after catless downpipes. sound wise, it doesn't get much better than a fully catless exhaust with a resonator and good muffler (cp-e for the 135i, berk exhaust with catless downpipes).
and yes, i agree that combining all of our knowledge into one thread would make it much easier to search. i don't mind staying on top of this thread, i'm online all day at work, sometimes i get bored.