I road race my 91LS with a 98GS400 driveline. The shifts are slow and slurred which is great for grandpa, but not great for racing - only the 4-5 shift feels at all crisp. I know about shimming the valves, but was thinking a fresh upgraded trans would be nice. Is the stock converter ok or do they need work? Anybody have experience with these guys? https://www.powerdynamix.com/store/Fully-Built-A650E-Transmission-p42753794