I can recommend this kit.
I bought it last year. I hesitated initially because of the costs, but this is mainly due to the low unit numbers and it is high quality processed.
I have inserted the stainless steel funnel so far into the intake hose that the overall length of the intake is tuned to the rev range with the highest performance. With my engine this is the range from 4500 to 6000 rpm.
The effect on my GT with the Hitchcocks Performance Kit is amazing, once the funnel slipped out of the hose and I noticed immediately the reduced engine power at high revs.
Great workmanship,
Jerry