Polo have you broken any drive shafts with the welder? Apparently on the 350z's used for drift lessons out there, it's very common to break drive shafts.
I broke no shafts last year, and two near side shafts this year. That's with a 305/30 19" tyre and 675hp, shafts are weak but not as weak as people make out. Obv transmission lash is a lot to be said for, keep tolerances tight and replace worn shafts. They use a Gtr inner cv joint with gtst shaft and outer joint. I'm converting my hubs to take the Gtr wheel bearing so I can use Gtr shafts. Biggest transmission prob with these is keeping the diff attached to the car, the single rear stud sheers, I had it happen at knockhill, smashed the prop, exhaust, fuel tank and front to rear water pipes. For that, keep all subframe and diff mounts stock, also prevents the common problem of rear subframe from cracking/splitting. I was going to look at modding the subframe to take a twin stud back plate like the s and r body but one stud sheer in a very hard two years is manageable.
Just to add those shafts I broke wer doing angry mega burn outs during the up shift and 1/4 mile at pod.