My current setup is flowmaster 40 series, and 2 rear cat deletes. I plan on a K and N air intake, Headers and a tune. My question is if I buy shorttubes would I get any gains at all? And would i lose power with the longtubes because of a lack of backpressure? I used to be a mustang fanatic and it was uncommon for someone to have the longtubes if they had under 350 at the wheels. I have the 4.6 2wd. Any help is appreciated thanks