I was going to buy a Mark 1 Focus RS but I bought an M3 instead.
In a nutshell the M3 is built to do do it's job perfectly, modify a Focus RS (lovely car) and you'll have to uprate certain parts like the clutch

I had an ST225 which was remapped and it was a great car but it ripped the clutch apart and the front tyres despite driving carefully.
I use my M3 as my daily driver and my Subaru as my fun toy, it's the wrong way around I know but I don't care about breaking the Subaru but I do care about breaking the M3