Q45 diffs are pretty strong. I had one in my 240 for a few years , dyno at 600hp/600 tq. You have get the right Q45 diff for your application, did you know they had to different diffs for the Q45?? 90-95 diffs had 3.50 ish final drive ratio and the bigger input shafts (30 spline) 96 and up had the 3.69 ish final drive ratio and 29 spline input shafts. Axles need to be made. That setup was the smoothest running diff I had in the car, no clunking/noise. I sold that setup years ago on Hybrid. I wish I would of kept it. I curently have longnose R200 lsd from 300zx turbo installed now, it is holding up to thoses power levels. But a little noisey and clunky. I am waiting to install the q45 diff back in the car after the first of the year.