I am running over 200 without dumpvalve. A turbo spins up so quickly you won't notice the difference with or without.

The airfilter is simple. The more restriction the less bhp. A clean airfilter will performe better then a dirty one. Its one of the many factors that are important if you are trying to gain max performance. A quality one will do better then a bad one. I am running K&N inlay in a standard filter i believe.

On a dyno you might already not see the real difference between air filters as on the road air flow is different. Difficult to say what is better, just look for yourself. The engine needs the coldest air. I think a standard filter performance is better then a cone. Underhood temps are high at an escort