I'm not sure what others are doing, but for example....running an old pan in club races here, and running a Picco 21 that I think I bought in 1982. It has all the punch it ever did, it's got a tame idle but all the power in the world.
Discovered early on a little judicious porting of the exhaust and deburring elsewhere is about all most engines will ever need. I still do the same thing with todays engines and get just about the same effect.
I don't use any "tuners," or temp meters. I was raised old school and found smell and sound is about all anyone needs to get the engine where it has to be. I understand everyone has to go with what works for them, but over the years I tried to look at tuning as more an art than a science. I have a shop where I do the real thing (full size engines) and you'd be amazed at what works on the big stuff still applies to the small stuff...an engine is an engine is an engine.
What I'm basically getting at is you can get all kinds of motors, and if it doesn't have a built in limitation like exhaust port way too small (that thing they call an engine that comes with the Kyosho RTR is a good example,) then you can get good performance out of nearly any engine. I'm currently runnning S&H motors which I find are ridiculously cheap but hold their own against lots of top end (and top price) motors. I try not to run anything lower than 40 percent....an engine born and bred on the good stuff seems to get stronger with age (must be a metallurgic thing.)
Side note, I've found some engines actually have too large an intake port and the engine is consuming way more fuel than it can actually burn. You can play with that thing all day long and get ok performance but waste a ton of fuel in the process. Sometimes less really is more, and some engines you can put a restrictor in and get better performance than not because you can tune it more accurately (less rr's needed to clear the unspent fuel.)
Just my two cents worth, but in this economy, may only be worth a penny!