brake pipes, fuel pipes, fuel tank straps, and the fuel tank itself, fuel filler neck, thats about it from the underside matey.

the track is wider on the frs so the hubs, wishbones, front cradle, full rear beam are all rs specific.

the underside of my frs has been in parts and powder coated/ polybushed all in the last 12 months mate so seen all the problems.

you could in theory get a complete rear beam including all brakes, the whole lot and swap that over, and you could do the same with the front but you`d also have to get all the hubs , suspension, steering rack e.t.c. and use some driveshafts from a 2.0 or tdci.

the differences then would be you track wouldnt be as wide and youd have shit brakes.. tell the insurance youve ruined your car haha

but at the end of the day it would probably be cheaper and a lot less hassle to buy a shitter thats clinging onto a months ticket and test and rrun that while the rs is off the road lol