S52 cams = Between 600-1000 at most for cams and install
Intake - 150-200 and anyone can install this but it has to have the m50 Throttlebody too
Don't need injectors unless you turbo. The injector poundage is the same in a 2.8 and m3.
Cai - 250-350 and can install yourself
Headers - Already have stainless steel headers on the 2.8 and I see no reason for anything more.
exhaust - 600-800 bucks for a good one and will need to probably be professionally installed which won't be much
pullies - 150-200 can be installed by youself
shark injector - 350 I believe
Taking these on the highside this totals about 2900. More then enough to do a tranny conversion and add a LSD Differential if he wanted. Heck, I'd do a 6spd swap if I were him. This would be one smokin' machine :P Also don't forget the fan delete mod :P
Other awesome items which I'm getting are BAVAUTOs fuel pressure regulator, big throttlebody, 3.5 mass air flow, AA Track pipe, oil cooler, and lightweight flywheel and pressure plate.
Or you could screw all of this mods and just say fuck it and buy a damn Supercharger for about 6000 :P. Your auto would be badass with a SC haha. My goal for my car was to get everyone bolt on upgrade possible pretty much so that I'm maxing out my car's potential and then I'm going to go F/I.