I'll help pay it forward...I got a 2012 135i similar to yours last year as a track car. It was stock. First track season for me was also last year (why I got the car). Your skill level is likely low so I would not do ANY mods, only preventative maintenance(definitely do the Motul 660). Do get good pads if your pads are worn (I use Ferodo 2500's). Check all the stuff you will find on track day tech inspection sheets. Then, after your first couple track days, the things you need/want will start being obvious.
In summary from a guy only one year ahead of you with the same car...
- Make sure car is good mechanical condition (no issues, fresh oil and filter, no leaks, etc). BMW actually does BMW CCA track car inspections regularly so that may be a good place to start.
- Swap brake fluid to Motul 600/660 - brake fluid swap is probably needed anyway.
- Make sure you have good life on your brake pads. If not, get some street/race ones. I got Ferodo 2500's. First track day this year with them was awesome.
- the only other things I would do before track day are reliability mods---charge pipe (mine is ER), Titanium brake shims (for heat), K&N Intake Filter.
- Go to your first track day (better yet...do the BMW CCC first...my personal recommendation is join the BMW CCA...it's only $49/yr and sign up for some HPDE's. This is a great way to start from scratch IMO)
- Take notes at the end of the day of what you felt your limits were..braking? Traction? IATs? Oil temp? Power? Then develop an upgrade plan to ramp up as your skill improves.
Having said all that modding is still fun in and of itself. I am still way below the skill level necessary to get the most out of my car but I am slowly climbinb the ladder.
Things i did in my first season (and over the winter) in addition to the above:
- New FMIC - keeps IAT's down which keeps the engine happy. Mine is a Wagner but there are many good brands for this.
- Titanium brake shims (DS1371's). Yyou will discover, as you peruse the forums, that the brakescan be an issue with this car if you drive it hard, due to the ceramic pistons on the Brembo's up front. They are great brakes...just the pistons can get heat cycled out and shatter if you don't have mitigators (cooling, shims, etc)
- Custom brake cooling hoses and fittings - use the stock brake duct holes and route hoses to the back of the rotor hub. Very cool...but I can't talk about it much because I was a beta tester...
- Poly Rear Subframe Bushings replacement - mine are whitelines (not for the feint of heart...you really need special tools to do it right. Or you can pay a lot for someone to do it for you) Some swap in M3's.
- Second set of wheels and tires (used) for the track (I am assuming this is also a daily driver) as I was chewing up the outside of my stock RFT's due to too little camber. I just swap out wheels the night before a track day.
- Dinan camber plates (to also improve the camber issue). Others get adjustable ones from Vorschlag or another decent company. I went with the Dinans because they are relatively inexpensive and easy to install and, important for a DD...won't rattle like race-type camber plates can. My front camber is at -2.2 which is good enough for my skill level right now.
- Custom MHD tune from
WedgePerformance . Couldn't help it...he tuned my 335i as well so I just did it. Pushing north of 350WHP and 400WTQ on pump gas. You don't need this...but it is intoxicating. The MHD stock maps are decent also. If you do this, get new coils and spark plugs also. Trust me...just do it.
- RE-71 tires for the track wheels. Really sticky.
Recently I added a real diffuser (
http://www.1addicts.com/forums/showp...93&postcount=9 ) - just for fun.
and a Mason strut bar...didn't notice a problem with stiffness but it was a good deal...not sure if I'll notice anything at my skill level but I know it makes the front stiffer than stock. We'll see on my next track day.
Things on my list after this track season and maybe the next (although right now I don't need any of them, honestly).
- M3 control arms front and rear. (lighter, also pushes front camber out and additional 0.5 degrees or so)
- New sway bars front and rear (still trying to decide which ones)
- Coilovers (still haven't decided on these either)
- Front splitter (probably the full set from OMGsplitters)
- LSD - probably an Mfactory
- At some point I'd like to add a PPK2 kit that puts the extra water cooler in the drivers side wheelwell.
Having said all that...my goals are likely different than yours...I want a trackable street car, not a streetable track car, at this point on my journey. The order of the words is important...
Oh...and I personally don't think the N55 needs an OCC (N54 does - my 335 is an N54) but it's a good simple initial mod and won't hurt anything.
HTH and YMMV.