I had a ST205 WRC and now own a GTiR, and have done for 4 years.
Imho, the GT4 is a much better alround package. The handling out of the box is far superior, the brakes much better (315mm disc up front with 4 pot alloy calipers, 300mm discs at the rear with 2 pot alloy calipers), the gearbox is much stronger (said to take 600 bhp in standard form iirc) and the engine is just as good as the SR20DET, if not better in standard form. You'll get 255 bhp and 215 ft/lbs iirc from a stock import. With a few very cheap mods to remove the ecu boost control (it limits boost in 1st and 2nd gear) and up the boost to a safe 1.2 bar (just under the fuel cut), you'll get 310 bhp and 290 ish lbs/ft torque. That'll make a very fast car. Mine had a Hayward and Scott full exhaust with 3" elbow and downpipe into a 2.5" decatted system, Blitz SUS filter, lagged charge cooler and about 14 psi of boost and I could keep up with a mildly modded Evo 6 TME with an extra person in my car. As for the R being much quicker, I'm not so sure. I had a play with a fairly standard looking import ST205, a couple of years back and he could keep up with me. I had 2 extra people in the car though and was only running just over standard boost. Having said that, my GTiR now, can stay with TVR Tuscan's and the VXR 220 with a few extra mods and a bit more boost.
Fact is, the GTiR weighs around 1220 kgs and the ST205 around 1380 Kgs (same as an Evo 5 and 6) so, you can make you own judgements from that but, I can tell you a mildly modded ST205 with decent decat exhaust (including larger elbow), lagged charge cooler, large intake filter and 1.2 bar of boost will be very quick.
The chargecooler won't need replacing unless you decide to go over 400 bhp, the OE clutch will handle about 350 bhp/ 310 lbs/ft torque no problem, it has a large air to air oil cooler as standard and an alloy bonnet for lighter weight and better weight distribution
The interior of the GT4 is of a much better quality and you sit in the seats, not on them as you do in the GTiR. All in all, the car is built much better and wont creak and rattle like the GTiR does. It's also very comfortable, a proper junior GT car.
Only real thing to watch out for on the ST205 is the front suspension. Due to the design, the 'figure 8's' will wear quickly and these will need replacing every 50k miles or so. Not a big expense if you know about them. I didn't and ended up shelling out £1000 on OE suspension parts for the front end to cure the knocking !
The only reason why I got rid of mine, was because someone drove into me on a perfectly straight dual carriage way and caused £6800 worth of damage to the front end and so, it got written off. Then I bought the GTiR. if I had the opportunity to won another one, I'd not think twice about it !
Not that I don't like the GTiR of course !!
