Just a note, having a 310s car myself.
I looked into getting throttle bodies fitted, but as its running variable cam timing, that also means new ecu etc etc.
The cost would pass the £5000 mark, and need much setting up on a rolling road.
I have a light weight fly wheel and 5 speed Mazda box.
The throttle response s instantaneous.
I had tried a 360r and 420s with 6 and 5 speeds.
BTW the factory stock or modified car will always retain ore more value than an aftermarket modified car.
GP cars in kent have had a premier power modded 7 from Oxfordshire for many months.
Its your money and your car , so choose away.
Best of luck.