Im just goign to give soem of my opinions on the above posts.
Good
brake pads have been recommended. I would also recommend PBR Axxis Ultimates. They run about $62 for fronts and $45 for rear pads. I use them and have always used them on my cars.
As far as
Brake Rotors go, this situation has always been argued and the final educated conseus really comes down to logic and little bit of science. For the best single stop braking power, OEM blanks would be your best bet. They provide the most surface area for pads to maintain full contact with. Vented/Slotted rotors are also another top choice. These are the best at dispersing heat away from the pads/rotors and help alleviate brake fade. Cross drilled are "supposed' to work but we can all just assume they are primarily for show. UUC has some great rotors, and I think they even sell vented and "dimpled" rotors that give the cross-drilled-look without the instability in products that may cause cracking. A great site also that I always always always recommend because it's well organizied, easy to use, and has great prices, is
www.turnermotorsport.com
I am always skeptical of
drop-in air filter upgrades. I dont see how they would give you any gains. My opinion is to go with a legitimate proven Cold Air Intake system. im not familiar with all the cold air intakes for e46's and which ones are the best. What state do you live in? I dotn knwo if it bothers you but soon when you have to start doign emissions checks they might notice the CAI as a non stock part and may visually fail you. Some companies have CARB systems (liek Dinan) mainly for states like California. Take this into consideration.
As far as
suspension goes, I could get into a 10 page paper about this. It seems youve doen a little bit of homework and know that you want to do more than just teh typical struts and springs. Good move. Im not goign ot recommend you go with a coilover system because the price range is similar for lower coilovers vs. springs w/ adjustable struts. What im sayign is the coilovers in your price range are probably a bit too stiff for your liking even though you can get ride height adjustability. My recommendation is you go with H&R sport springs and with Koni SA (single adjustable) strut/shocks. These Koni's allow you to adjust dampening force (how soft or stiff your car can ride) easily through the top of your shock tower. You will adjust this way mroe than ride height. As far as Anti-roll bars I dont know the factory sway bar specs but for this ill recommend
www.uucmotorwerks.com. I dont know the oversteer/understeer characteristics of your car but im sure theyve learned it and put time into it. Just make sure you are doin an upgrade and not gettign the same size bar (much like ive seen Racign Dynamics do in rear bars).
Youll love a lot of
exhausts out there. Ill just tell you to stick to brand names, and stay away from UUC TSE and Gruppe M unless you like ridiculously loud exhausts.