BT escorts feel quicker because the power/torque comes in with such a bang, the ST escort has a flat torque curve hence feels physically slower but I assure you they are not because they have the power available more of the time, so general driving they are much better IMO.

Real world example is my mates 2wd saph cossie RS Lozworth of here and that is a stage 1 on a T3 which I thought was MUCH quicker than my escort, however on a recent jaunt he said he couldn't catch me, so take into account the 4WD tranny losses as well and this proves a point.

You will be very lucky to get 300hp from a small turbo, maybe with a change of cams, for example GGR305 conversions were/are notorious for not achieving the claimed figures, and I think if you speak to any tuner they will tell you 305 would only ever be achievable on a spike, not particular useful.

Having owned both cars I would not assume the BT is the daddy because I found it quite frustrating at times, and genuinely prefer my ST car as it is compared to my Stage 3 BT as it was. Having said that I do want 400hp/400lbs as my Evo was 350 and now I want to go a stage further and that aint gonna happen with the T25

If you are going to chip your ST expect anywhere between 260 and 280 hp I would say, it WILL feel quicker, but you WILL want more

I have the standard airbox still on mine, and the general feedback I have recieved is that this is good enough for 400hp so unless you want the induction noise don't bother.

If you have the zaust then you need a chip, fuel pump and an actuator you don;t say exactly what is being done for the £1,000 but this seems a little high to me, the £500 notes seems about right