You really shouldn't worry about ITR suspension for now.
ITR's come stock lowered, and even if there is an ugly wheel well gap, it won't really be a problem if you just buy a set of 17s. If not, then go with the coilovers, I'm pretty sure your shocks wont be a problem. However, that austrian guy is right about performance. If you get coils, your suspension might be offset, because it unbalances the adjustments. I think you should get a suspension kit, because dealing with a TYPE-R's suspension isn't something anyone normally would do.
I lowered my GSR 1.7 inches in the front, and damn, it feels as if the shocks are going to blow any minute!!!!

well, tell me how it goes.