Whilst I think the 4.1:1 axle mod is a very good one- for me the biggest change to the car came when I fitted the Aero Throttle Bodies.
If you add the Aero manifold, cat and exhaust the bottom end is improved ( but the Sigma is never going to have the torque of a V6/8)
The Throttle Bodies with the remap just make the sound glorious - and the top end revs intoxicating.
Not a cheap modification - but value is in the eye (ear!) of the beholder !
