My personal experience with 5-speed TKO is with a Modular Mustang Racing beefed up TKO-500. The engine I have that it behind is a 408". MMR chryo treated the gears and did some shifter work and made it good to 700 lb/ft / 700hp. In the TKO you have 1,2 on a separate shaft than 3,4,5. This causes a major bummer in speed shifting. The tranny is great to shift through except for 2-3. You have to shift 2nd - 3rd gear like a dump truck. Fingers crossed but I have heard of quite a few TKO failures from a combination of grip, RPM, and the 2-3 shift (even in light cars with street tires). Spirited driving is fine but, just remember, the TKO is NOT a trans for drag racing an you'll probably never have a problem. I can't say for sure what RPM I'm running at 65 mph in 5th but I have 3.55's with a 228 @ .50 cam on a 114 LSA and she's in her sweet spot.