depending on if the rst is standard and you want to keep it a rs turbo engine then for 3 grand you can have a powerfull engine i only spent around £1000 on mine i had a t3 turbo kent cam with pully airtec intercooler and radiator and a omex ecu iv got a reliable 178 bhp as i use to use the car every day i can get 200bhp but for an everyday car i wanted it to be very relaible (at the time)

you can have a big valve head steel bottem end im sure theres a lot more mods out there as its an old engine

and it helps i do the work myself lol as for tuning i go to s.r.m.c as i cant fine tune the ecu