The conversion of my Impreza from 5 speed to 6 speed is nearing an end. The exhaust now clears the rear crossmember and is also secured at the rear of the gearbox. An unnecessary bracket fouling the floor was removed after considerable effort. As a result there are no squeaks or rattles, and the engine is now giving full power. I suspect the exhaust fouling the crossmember and/or the bracket fouling the body may have been picked up by the knock sensor.
Anyway, the thing is a rocket and has staggering levels of grip. Even on dirt I can floor it with full boost and it just steps out slightly and rockets ahead. The biggest difference is in front end grip- the thing just turns in like never before. Hard take offs on slippery surfaces and the car will follow the camber of the road as it slips down, but you have to expect that with all 4 spinning.
Wheel alignment is tomorrow, but I did a quick check while the car was on the hoist today. With no central point to get a true reading, there was 20mm toe out using the trusty tape measure. No wonder the car was a handful to drive. I did a quick adjustment and reduce that to 5, which while more than I want is LOTS better than 20. I suspect they are both pointing to one side as the steering wheel is offset and oversteer never seems far away.
So I am so far extremely pleased with how the car performs and I think the wheel alignment will justify my enthusiasm.