He might have had a K04 turbo upgrade but I don't think a K04 could keep up with a stage IV WRX.
If he had an APR stg. III the he would have pulled from you on the highway.
I don't think there is much in the way of tuning between these 2 options.
As far as I know the 1.8t mod plan is as follows:
2) K04 turbo upgrade good for 240hp
3) APR stage III
There might be some middle ground with different turbos but I don't think so.
I think a Blue 20th Anniversary Edition with an APR Stg. III would make an excellent car.