The exhaust will be fine, but the gti manifold has the wrong grading. you could try lathing it yourself (very tricky though).
Why not just flip the assembly brackets ?
The didn't put an auto-Q-lock on the 1.6, so that the actual-weight and the real-weight balanced out. That's why the control is smack on, but the push is a bit combobulated.
Yes, you will have to change the manifold and exhaust, Plus you will have to change the brake disc and pad's too. Or you willn't have good enough brake to stop you. But don't forget to tell your insurance, or you will not be insured to be on the road. if you have a crash. You might have to change you surspension to get better handling, because the engine is more heavyer than a 1.6. P.S be careful