I wouldn't consider anything made by 3 Racing a hop up...more like a down grade. The C/F is thinner and of a lower quality. Best bet is to skip it.
The very, very ealry IRS input shafts (about 5 years ago in the early days of the TC3) were a tad off. I haven't had any problems with them since (I ran them for 3 years in 2 TC3 and currently run them in my 2 TC4 and they are factory perfect!!).