TopherSho said:The problem will be unless you are injecting the techron or any cleaning agent into the intake upstream the backs of the valves will never get clean. we run in cylinder injection and the gas cleaners only hit the cylinder walls and maybe the piston on the up-compression late spray stratified charge.
The unfortunate problem. In another video, that same tech mentioned the use of catch cans (although he said they would void the warranty), use of the Techron (as you mentioned it also doesn't do much about the valves/runners, just the little bit of valve overlap that may occur), and using a high quality full synthetic oil, that will resist building up in the runners once it gets dumped back in through the PCV valve.
Sounds like really the only "safe" solutions are new heads or a thorough media cleaning of the runners. I wish that I could've got out in front of this issue, but it is, what it is.