it was basically that the frames were too low! Normally the GTI seats go in the runners that are basically part of the shell of the car!
Yet when you use the new frame, they go into the floor, well thats what mine did! So you lose the height of the runners, and also the height of the cushion of the seat, as GTI seats have quite good bolsters!
so when i placed the seat in the car attached to the frame, i could barely see over the wheel! But to your luck it could be different, put it all in the car and see how it sits! If it sits well, then get em in, if not, you may have to tinker with
bit of DIY fabrication!
But if your after frames , the clubmans are stocked at halfords, i know as i bought some when i was 17 from there, they will befo be able to get frames in for you!
Jake