the type r manifold will not be a direct bolt on for the gsr. you have to modify the head to make it work. some have done it just search some sites. but as gssr stated the skunk2 manifold is almost an exact replica of the type r manifold. it has the same concept of using one port and not two like the gsr. so, you will definitely get a better performance out of it. but don't expect it to make a huge change because you have to do other mods to make it do that. but i also read on the sites selling the skunk 2 is that it affects emissions, so if you do decide on that don't sell your manifold you can install it when you get the emissions checked and then switch it back.