Hi Baz when i got my93 it was standered.So i changed the ecu for a Z4,changed the air filter and the fuel pump for a walbro 255 and put on a fall decat exhurst. I was told by the guys at power engineering if i made those small changes i would be looking at around 280 -285 bhp. Since doing this my scoob feels so much alive now!!!
To do these mod's it does'nt cost that much if you shop around. For the Z4 your looking at £100 for a second hand one and this can be remapped for about £500 ish coz i've already spoke to Jolly Green.The walbro 255 is about £70 - £80 and the air filter i think i payed about £25.
I hope this helps mate.