I have just fitted a Sparco seat in mine. I bought a subframe and slider kit from GSM performance so the seat can be slid backward and forward.
Slider kit was £30 I think and i got the subframe 2nd hand from ebay. You just need to sort the airbag loom out if you want the rest of the airbags to work. I read the airbag light is on the dash then none of your airbags will work. I solved this will a Recaro kit from GSM. 20 mins to fit.