I don't have the answer but my suspicion is that Dinan would be best. There are a couple of people on this forum who are experienced on the track and have recently installed Dinan springs. I am hoping to hear their impressions. I really worry about making the car worse with lowering springs. I have a friend that put H&R springs on his 335 and it was bouncy at speed and he regretted it. I'm also concerned with the issue of having problems with the EDC while having lowering spings on as these units cost a fortune. At least with coilovers you are not going to damage the stock suspension because it is replaced. With the cost of installation and alignment I want to let the issue play itself out before I make a decision.
AW on Fox Red Extended, Alum trim, ZPP, ZTP, DCT, 19" wheels, Heated front seats, HD radio, Sat radio, I-pod & usb, Premium sound, AP racing BBK, 18 Volk Racing TE 37s, Akrapovic Evolution exhaust, AST suspension