[The_bluester (Paul)]

I would not ever bother with the old "Fool it with resistors" stuff. That really only had a place a couple of decades ago when aftermarket ECU's were rare and prohibitively expensive and factory ones were mysterious black boxes. A semi factory hotted up model (The Australian built Nissan Skyline GTS2) had an "interceptor" add on module to modify inputs and/or outputs to make it run properly with the far wilder camshaft they fitted to that car than the factory one as even for SVD, modifying the factory ECU was a no-no in 1989. Now with an half reasonable aftermarket ECU they would make more power, produce lower emissions and be nicer to drive!

Modern cars don't leave a whole lot on the plate as far as easy gains for a retune to be worthwhile, not run of the mill petrol models anyway.

Alex, if it is anything like MX5's of old, the top half of the rev range is where it will sing! A friend had a nice NB at once point and reckoned for an enthusiastic drive on a twisty road it really wanted to be between 4 and 6 thousand RPM to keep it awake.