How big is too big?

[Coc-ker]

170 odds is fine on standard tmic

I'd disagree with that point. IMO on any sort of warm ish day even on a light tune the FMIC gets HOT, never measured it but like probably 60-70*C. On a FMIC after a blast the cooler is often actually cooler than the ambient temperature. Lets put it like this, one of the days I tested it it was 16*C on the car thermometer and 12*C on the cold side of the FMIC. Were talking a 50*C difference there between TMIC and FMIC and if you believe the theory that every 10* drop in temp gives a 1% increase in power then on a 170bhp car your talking about the best part of a 10bhp difference

Pretty much this. Might be fine when moving but as soon as you sit at a set of lights, there is no airflow and it's useless until you get moving again.

When do you need boost when stationary at traffic lights?

Tbh this topic has been done to death. You will always get better throttle response from a top mount and you will always have better charge temps with a front mount (ish). I'd only consider going front mount when charge temps are ridiculous and the figures it's making are miles off what it should.

To put it into perspective Newage Impreza top mounts are capable of 400BHP easy.

Tim.