Stick with the standard manifold (I assume you have a 355). I upgraded my 355 (COME) Calais to a Motec ECU/TTB and was not happy with the result. It wasn't until I upgraded to a 383 with different (still mild) cam that the car started to perform as I expected. My advice would be to save your money. The 355 with a standard manifold will give you more than enough power (and more importantly usable torque) for the road. In fact, the 355s are deadly on cold tyres if you give them a boot taking off from rest!