Car is an 87 tii with a tbe straight pipe, stock turbo, and hks bov. Everything else is stock.

white smoke only comes out when shifting from 1st to 2nd or downshifting from 2nd to 1st. What is causing this? Turbo or O-ring seal on the 13bt?

 

It's probably a coolant seal, when I got my S5 it smoked really bad, but it was black. And it was my rear oil seal. I've heard many times that usually white smoke like you are talking about is usually coolant, it could be the o-ring possibly as well

 

it could be the oil control rings, had one that would smoke at high rpms on throttle lift off