so i have been doing a lot of research before i get my trans rebuilt, and was wondering at what hp level will i need billet shafts. i cant seem to get any solid numbers. i got a quote from a performance shop for $4200 for a rebuilt trans with billet tc,vb,high energy frictions, extra frictions in all clutch packs, converter lockup controller, and billet sonnax upgrades. they claim it will handle up to 525rwhp. does this sound accurate? ive heard flexplate and input shaft can break at 400hp? i plan on getting close to that 400 mark will i be ok with this trans? does it sound like too high of a quote? any comments are appreciated thanks.