Resonance with new Trans and Diff mounts?

[AndyW]

So, I made the mistake of having several upgrades done at once and am trying to track down some new noises.

I had the following done:

Wavetrack LSD install
Berk Mids (already had Race axle back)
S55 Flywheel
Poly DCT mounts
Poly Diff mounts

Car had VTT Engine Mount inserts and didn't have the new resonances. I am aware of the S55 rattle and it is present and understood.

I have a pretty strong rattle/resonance at 1200-1500RPM and another in the 2.7-3K range (less intense). A simple upshift and it disappears. Seem to be in the transmission tunnel area.

So track friends told me it is normal to get some resonances when you have all stiff mounts...or is this something I need to troubleshoot?

My biggest concern is that it might be the actual transmission or something else (exhaust not tighted up?) and don't want to dismiss it out of ignorance. Figured I'd ask here before jacking it up and investigating. Thx.

[SKI-R]

It was tranny mounts that created it for me (build: M3 rsfb, poly Diff, REVSHIFT poly motor, also WAVETRAC) - swapping to Rogue Engineering for the tranny resolved it even with a chassis mounted shifter. It’s a simple enough swap to remove them from the list of possibilities.

[135]

I'd say it would be the trans mounts.
I have solid mounts for engine, trans, diff and subframe (RSFB), as well as a diff brace. After installing the solid trans mounts (together with some other minor changes), I noticed significantly more teeth-chattering NVH at idle and as it progressed through the rev range. To determine the cause of the increased NVH, I changed back to stock trans mounts and the NVH was reduced to previous levels. I eventually put the solid trans mounts back in and the NVH didn't seem to be as severe, even minor - obviously my tolerance (and want) for NVH had increased.