They said it..
Yes u will notice a difference in the performance with the head. It will also help cool a little better, and looks ALOT better than stock.
If and when u decide to install an aftermarket head, I suggest the Noss heads over the rest, for a few reasons. Quality is awesome, fit is great, easy to install, and the customer support u get from David is awesome! When u are ready, PM him (dlnoss) he offers a 10% discount to HQ members, which is always nice!