Right... so while buying the G40 engine and gearbox, I also bought an G40

almost standard, some stupid modification which can be rectified easily. Some small things to be fixed, nothing major. No rust at all. Freshly rebuilt supercharger. Soooo, plans changed a bit. First, I want to bring the G40 back to original state. Then, I would like to put some performance upgrades on it.
- According to the owner, the car already has G60 injectors. Does it mean that with a G60 lader, small poulie and software I can get some 160-170 reliable horses?
- which is a good G40 sports exhaust? I don't need noise, but more flow. Can I just remove the cat with no consequences?
- brakes: Wilwood had some, but no longer for sale. Is there a way to put 4 pot bbk on it (maybe with 14" golf wheels). Or some better brakes from another model?
- anyone experience with KW coilovers? Or TA-Technix, which are half the price?
Thanks a lot in advance