ECM question

Looking for advice and thought I would throw this out there seeing that there is some pretty knowledgeable folks on here. I will come right out and say this is not my area of expertise when it comes to tuning. My truck is an 01 and has a C15 in it with around 950k. I bought it from the original owner and she runs real strong but I believe it will be needing injectors soon. The truck has a good tune in the ECM to go along with the marine cam and large turbo that was added before I bought it. It was done by a private individual with a laptop that knew his stuff. What im worried about are all the horror stories I hear about Cat dealers updating the ECM when guys have there trucks in there for whatever. I spoke with the local Cat house here and explained to them my concern and they said due to the year they wont have to touch it seeing that my injectors are at stock code settings right now but people tell me not to trust them. There is another shop close by and the guy is a self proclaimed Cat guru but he insists he can probably still make the truck run better with his tune. Is there anyway to back it up on some software before it goes in? I guess im just afraid of getting it back and having it run like crap.

 

Thanks, that is pretty much what they told me and because of the year would be ok. I have never had it on a dyno. Just real happy with the way she runs, not many hills here in the northeast that I have to drop many gears on with 80k. Still manages to pull in 6mpg. The oil samples have come back good other than slightly elevated soot. When you sit at a light long enough sometimes she will start to thump a little, wouldn't call it a skip and will run a little rich. It clears right up when you bring the rpms up. I know 2 and 5 have been replaced. I was figuring having all 6 done at Cat since its the only way they will warranty them.

 

I spoke with them awhile back about this, IIRC it was going to be around $5k for all. But this is the dilemma I am having LOL. I have a lead to another private individual who was recommended to me that is "suppose to be good". Thinking about paying him a visit as well.