Why is it that exhaust manifolds where a foreign language some two years ago and now everybody can come up with them, make them etc. It seemed like Greddy was it and nobody else didn't do the Z do to fitment ( I assume ) or after market turbo availability. Then Pentroof was being tossed around with the heavy wait time and price tag. It seems that now Zer's can get them from now both East and West side of the states from vendors on here and still Japan. So the price will be very competitive and favor the consumer. I seen Mal1ace's flow test floating around here, will these go on his chart or do you guys have those same spec's on yours, etc., as far as the design angles and diameters, bends?