I see a locked thread on the way... All there saying is the cat back exhaust really makes no difference in our cars unless your pushing big power because stock is good up to atleast 350ish at the wheels I believe before it becomes restrictive. Like I said demod it then list it for say 3700 and you will have the extra parts to make up the difference and the car will sell much faster. These guys know what there talking about with the 3800 so long story short there right but you do have good flow mods setup and just waiting for a pulley drop and tune.