I haven't dyno'd the two combos back to back NA. but years ago two of my buddies had 95 GTs. both had tremecs, 9:1 306s, F cams. both had vortech s trims on them. one had TFS TWs with a decent valvejob and an out of the box track heat intake. this one was making 13-14lbs of boost with a 2.75 pulley. then we had the car with the gt40 and another ported gt4o lower. it had a 2.95 pulley on it and made 11-12 lbs. on the same day, same dyno tuned combos the gt40 setup made 462 and the TFS combo made 478 with 2 more lbs of boost. so a difference of 16 rwhp. how much of that is boost and how much of that is the tfs being superior is up for debate. for reference, I have also worked on Kirk Jacksons bone stock longblock 24k mile 93 cobra back in the days before it was featured in MMFF. the lower had never been off the motor. with an s trim and a 2.95 pulley it made 12lbs of boost and averaged around mid 440 rwhp. so between that and the TFS combo the TFS kit made a little over 30 rwhp over a STOCK 93 cobra motor that was making 2lbs less boost, as well as the TFS combo above having the benefit of a larger cam. so im not really sure where you are coming up with 50-70 hp difference with the TFS package on an NA 302/306? can you please cite specific cars that you have worked on?