After driving the truck w/ the ls2 for a couple weeks, it pulls way harder up top than the truck intake. But I really need to get my tune fixed to really say if it was a performance mod or just cosmetic. I will say this, having the ls2 injectors(42lb) versus the trucks(25?lb) may be where the difference is coming in, since the same tune is in, and holding the injectors open the same length of time?. I'm not a tuning guru.... yet, so forgive my ignorance.