1/2) realistically i think you'll see 20whp from each part alone, give or take. theres alot of dyno variation involved. combined, 35 to 40whp. i know some companies claim that thier test pipe or downpipes give alot more on thier own, i feel thats dishonest and unrealistic. from a full turboback exhaust i would say 40whp is reasonable to expect.
3) you think its possible to get 10 people for this? i'll take another 5% off if we can get even 5 people
4) the corksport package (test pipe, down pipe, cat back) will probably give you slightly more power.