Originally Posted by qik40t
I have a 05 ba xr6 i got told if i go for a colder thermostat i will go a bit better because it will feed more fuel i it
It is true that a colder thermostat (or removing the thermostat) will make any EFI car run richer, but in no way are you gonna feel any power increase. All this does is confuse the PCM into thinking the car is still cold when it's in fact at normal operating temp.
So, when the car is cold you won't notice any difference and when it gets hot the PCM will dump excess fuel into the cylinders without letting more air in, so you still won't notice anything except a fuel smell and an awesome fuel bill. Long term dramas: O2 sensors and Catalytic converters fail if the engine is constantly running rich. You also get carbon build up inside the cylinder head, manifolds and throttle body and probably the engine light on.
Up to you, but I wouldn't do it. cheers