this is something I know a bit about!!! I currently have a 4spd ba xr6t making 330 odd rwkw daily driven, 380rwkw on my drag tune which is occasionally street driven. Soon to be making 400rwkw... hopefully!!! I have had my car just over 4 years now and bought it 2nd hand with 45000km on it. it has now done 116000km my car has lived with 300+rwkw for 3.5 of those 4 years, most of them sideways racing someone. I reckon in my car's lifetime that I have probably done at least 250 passes at the drags.. the majority of the passes were 11.6 or better. currently running 10.9@126mph.. my stock gearbox lasted 6 months making 310rwkw, though it did not have a trans cooler and I was not afraid of ripping a skid here and there. im currently on gearbox number 6. A built 4 speed will last me 14 odd months before it starts making noises with my car making 330rwkw+. once it does this I stop driving it until I can afford to get it rebuilt. I have smashed 2 rhs cv's at the drags. 1 was my original std cv which went out of the blue at the drags. and my 2nd was due to launching my car with 18psi off the line. My engine has never skipped a beat, though I have never skipped an oil changed and it is always changed every 7500km or earlier. My engine still has perfect compression after 65000km making 330rwkw daily driven!! as to how long components are going to last, here are some tips to help extend their lifespan: - dont down shift your 4 speed auto (engine braking) they dont like it and doing it will kill it really fast!! - if your doing a static burnout, dont hold it too long in 2nd gear!!! - dont be doing power slides all the time!!! - keep your oil changes up with quality full synthetic oil ( engine and trans) - instal a trans cooler for your auto - dont be tight with money and mods, it might cost more to do it right!! listen to your tuner!! - try and stick to the same service station - dont drive on your max hp tune last but not least, a decent tuner will do wonders as to how long your engine and gearbox are both going to last!!!!