| I haven't used the UUC mounts but I've heard the UUC mounts use a soft poly that doesn't transmit a ton of vibration. They do however label them as being for track use only. There are also scattered reports of failures with these mounts. Some pics and discussion here:
I personally wouldn't touch a non-bolt-through poly mount.
For a mostly street driven NA 330, I wouldn't recommend anything stiffer than the M3 mounts.
04 IR 330i ZHP | ESS TS2+ SC | MagnaFlow "headers" | KMS 3.64 LSD | AST 4100 550/650| APEX ARC-8 18x9 | H&R front sway bar | Vorshlag camber plates, RTAB limiters | TMS subframe & swaybar reinforcements | UUC SSK & DSSR | UUC TM & TME | BW motor mounts | Dinan strut & shock tower bars | vaio 4-bolt oil pump