In this market the ITR runs 10.6:1 and the GSR is 10.4:1. That accounts for a very minimal power increase.

Type-R retainers are no different than GSR ones.

Type-R intake valve springs are the same as GSR exhaust valve springs.

The B18C5 is what you might call a complete package with balanced upgrades across the board. You can however, top its output with different mods to a B18C1.