I ran a cpe rem on my 6 for ages then sold it for a jbr trilogy, had no issues with the cpe, vibes eventually reduced after a few thousand kms to the point it was really only when the ac was on that the vibes were noticeable. May be different on the 3. In terms of side mounts I have recently removed the drivers side and can safely say I do not miss the amount of noise and vibration that one mount introduced, so only have transmission mount and rem and think the transmission whine is easy to live with in comparison!
Good luck with your decision
Also, unless you can physically pick up the mount from mps garage I support the above re giving them a miss. Edge autosport in the us are great to deal with
AP V3 (Rayd tuned) / CP-E CAI / CP-E TIP / JBR Trilogy / CS Front Strut Brace / JBR SSP / JBR Shift Knob / JBR shifter bushings / Eibach Pro-Kit / Bilstein B8's / SURE Juggernaught / SURE Dreadnaught / Whiteline RSB / Toyo Proxes T1R 235/40/18 / Evo X BBS rims / Turbosmart Dual Port BOV / CP-E DP / CP-E TMIC / Autotech internals / Superpro bushings
Future mods:
BT, DM OCC, EGR delete, Braided clutch/brake lines, Hawk HPS 5.0 pads, DBA T3 rotors....