Sorry it was not clear...... We have dyno tested many stock turbo cars going from super split 2.5" and regular split 2.5" and then the only change going 3" expansion downpipes with 3 to 2.5" coned test pipes. All of these show major gains through out the power band and the largest gains being the low end mid range power. What we have not tested on the dyno with stock turbos is going from 3 to 2.5" test pipes and 2.5" cat back to just changing to full 3 inch test pipes and 3 inch cat back.. We have done this change and the cars feel faster, but we have not dyno tested this yet. The way I have looked it is the gain is probably fairly small on stock turbos to go with a 3 inch cat back, so if you already have a good cat back and your not going to upgrade your turbos it probably is not worth the money to go full 3 inch. If you have a stock cat back and your going to buy something anyway it makes since to go full 3 inch because there is not a down side.
