Decided to take a look inside my 300's cylinders today,but i'm not putor literate enough to get pic's off my boroscope onto here. After a bottle of CRC's 1 stop cleaner and a bottle of SI-1 ,the outer edges of the pistons towards the ring lands are definitely cleaner then they were last fall. The center of the pistons don't really show much differance,but it's tough to gauge the thickness of piston top carbon build-up,they might have less carbon then i think,but with-out pulling the engine apart it's only a guess on my part. The stuff does clean the carbon on the outer edges of the pistons though,and probably knocks a bit of carbon off the top ring land. I haven't really noticed any differance in injector noise,they don't seem to be any quieter then they were,but then again,they aren't any noisier either.
Whether it's a cure all for fuel system issues,i'm not gonna coment on,but then again,i also don't think it hurts anything either. If you have noisy injectors it's probably worth it to run a couple bottles of the SI-1 through the system,and see if it helps.
The stuff appears to work,maybe not as much as i was expecting,but i only ran one bottle of each through the system,maybe if i'd of bulked it up to 2 bottles of each per tankful of fuel,i might have seen more results.