I have been really happy with my R154. I like how the tranny feels, I especially don’t find it bulky but hey my last manual car was a mustang.
My first R154 broke after running some 12 sec passes, but I always knew that tranny had problems before it was installed, it was VERY abused. I know have another used tranny installed for 3 months with no problems.
Now for the heads up:
Your clutch setup can be vital to how long your tranny will last. My first clutch with the R154 was a stock MKIV TT supra pressure plate with a RPS UNSPRUNG 6 puck disk. Car had stock MKIV supra TT flywheel. Clutch held really well but when fast shifting, it banged the tranny REALLY hard since it was unsprung. I believe this was also a cause for the first tranny failure. Not to mention the clutch pedal was really STIFF, was killing my left knee. I also noticed that when my car was an AUTO, it revved much easier and went all the way up to 7200 rpms (haltech, higher rpm limit) With the manual tranny the engine felt much more lazy and would barely go to 6500rpms. I knew this was due to the extremely heavy 30+lb flywheel it had from the MKIV TT Supra.
I looked into getting a more streetable clutch with a lighter flywheel and found the following.
Exedy hypersingle for the 1jz with lightweight flywheel.
It cost around $1200 but they have it on special $900 SHIPPED!! This was an awesome price for a complete kit which includes a flywheel. I sold my old setup for $500 and got this installed.
The 1jzgte flywheel it has bolts perfectly in out 2jz. I only had to get a 1JZ throw out bearing and to install it. $25 US new part number 90363-45012 and a Clutch hub release for 1jz (made it custom $140)
I just broke in the clutch and here are the details:
The car feels it gained about 40rwhp! It revs back to 7k rpms with no hesitation and now the car has completely no traction in first and second unlike before. Can wait to go back to the track.
Pedal is around 25% softer than the stock supra pressure plate with 6 puck disk RPS combo.
Rattles less than previous combo in idle off clutch.
Holds fine up to now
Its a little harsher on contact (vibrates) when taking off in slow stars (has less slippage since its all metal I believe) But it has gotten better with time.
No more hard banging on the tranny with fast shifts, feels that the tranny is taking much less punishment.
Hope this info helps.