Just a few more points to consider, IMO:
- cloth interior is not desirable to buyers, so can be a problem to resell in future
- unless lowered, GT sits too high and looks wrong. I have lowering springs only, but that is not perfect. Different dampers were more than I was willing to spend (£1000 fitted for springs/dampers?)
- Unless you have bose stereo, standard headunit is pants. I have had to change headunit/front speakers and add a subwoofer in the boot for some bass!
- Anything less than 18" alloys look too small
- Standard 150bhp is ok but a bit slouchy. A tuning box or remap is what brings it more alive.
I have all of these, but they were done over nearly 8 years of ownership, so not noticed the £.
if i was to buy another GT, I would want the same again. If I look at my neighbours RX8, i don't think any of these requirements would be an issue. With your initial budget that you mentioned and planned mileage, I would be more tempted with the mazda.