I am curious to know from your experience how strong the stock 87-88 turbo transmission mounts are and what the upgrade paths are with more HP/ torque. I'd like to keep vibration dampening if I can, but if not I can deal with it.
Option 1: Stock
Option 2: Mazda Comp
Option 3: Others?

 

Not pushing a great amount of HP, 12 psi, but years ago when the mounts needed replacement,
tried the Mazda Comp mounts and removed them after a couple days, too much vibration, back to OEM.
Did leave the Comp engine mounts in place though.

 

Others, Super Now! has solid mounts https://www.rhdjapan.com/super-now-t...ange-fc3s.html
the Infini 4 used the convertible mounts, FB67-39-340, they are slightly stiffer than the coupe mounts (10%)

i think i agree with having stiff engine mounts, and softer trans mounts, the engine isn't designed to be a structural member of the car
that being said, i went competition engine and trans mounts, and i'm happy, although current setup runs really smoothly

 

I'm in the process of installing an S4 TII box currently and still deciding which mount to use in the crossmember, FB or FC. I'm leaning towards FC, but wanted to make sure that was not a mistake, due to any reliability issues I'm unaware of. I've been running comp motor mounts and a stock FB trans mount until now. It ran pretty smooth with an acceptable amount of vibration. I added the comp mounts when I had a J-Bridge because the engine was pulsing so hard at idle the old Holley I had couldn't keep the secondary seat closed. I ran the Cosmo Block with the stock porting and a low boost turbo for a bit and it was pretty smooth, some vibration felt in the steering wheel, but acceptable. Now the motor is street ported and I'm upgrading the turbo to an EFR 9180, so I am also trying to upgrade the supporting systems to keep up.

I have been toying with the idea of changing one motor mount to stock so I would be running one comp mount on the tension side and one stock mount on the compression side. Not sure if it would reduce vibration though. For the trans mount, I'm leaning towards using stock TII rubber mounts on the transmission, but looking for the forum's confirmation that this is not a bad idea.

 

If you're planning to be on the street most of the time then I'd avoid a solid mount. It's a stiffer ride. I'd stick to OEM.