First of all - hello, everybody! New to the forum, long-time BMW driver: 18 of the last 22 years, and again from 28 November: on that date, I'll be taking delivery of an ex-demo M135i xDrive (it snows around here, and it's my only car; RWD is fun but I need to get to the airport at 6 am before the snowploughs start running).
So, of course, two weeks before I even get my mitts on the car I'm already thinking of how to mod it...
Here is the "problem" - if you want to call it such: the car I'm exchanging for the Bimmer is a lightly tuned Subaru WRX STI... with about 350 BHP. Which means that while the M135i is a whole different world in terms of refinement, smoothness and - as long as the Scoob's pizza-sized turbine is not fully spooled - in-gear pick-up, in absolute, all-out terms it's a pretty even match. Which just won't do. Not to mention those pesky Merc drivers in their A45s (yes, I know, I'm having a kind-of-mid-life-crisis; I'm over 45, married and with children - and I'm showing the road maturity of an 18 year old. Sorry.
).
Anyway, kidding aside, I
have started looking at how to improve the engine; I may be wrong, but the rest of the car would be perfectly adequate to handle another 50-100 BHP on the road (race course may well be another question). The main objective of tuning for me would be to increase top end power/torque without losing driveability and smoothness; cost is relatively unimportant, as long as the improvements are considerable - €80/BHP is good enough for reliable mods. Containing noise levels to "acceptable" is also important - I have had enough pins stuck in my voodoo doll when going around with a racing motocross bike.
To this end, I have come up with a number of options, and would like to get feedback/experience/additional ideas. Options listed in order of likely implementation:
1. Re-map/piggy-back tune (BMS? tuningwerk? AC Schnitzer? anyone else?)
2. Replace downpipe with less restrictive cat (ER? AR? Wagner? another one?)
3. Replace intake and charge pipes (BMS? tuningwerk? ER? more?)
4. Replace intercooler (Wagner? ER? tuningwerk?)
Does this make sense? Would you do anything else/different/in a different order?
Thanks in advance for any input!