I love Petrucci's tone and I've been thinking about getting these. Would it sound any different if I put them in my Yamaha RGX120D? It's about 15 years old (I bought it used at a sale), and made of basswood. These old pickups have been in here since it was made, and you could say they're pretty muddy.
why wouldn't it be worth it? age of the guitar doesn't matter. if you wanna put them in then do it. older guitars with a more modern tone isn't a bad thing by any stretch of the imagination.
I don't see why not, Petrucci's signature axes are made of basswood and they're the pickups he uses, so it should help you achieve his tone. Of course, the harder part will be getting an amp as awesome as a Mesa Boogie Mark II C+... but, if you're not happy with the guitar's current pickups, it's a good idea to replace them with some good pups.
The guitar will most definitely sound better. I highly doubt you'll get Petrucci's tone tho. Maybe something similar, but just not there, you know?
If you've noticed in my sig, my amp generally sucks. I have a pretty decent stereo system that I can plug into that sounds much better (but with a dumpload of unnecessary bass noise) but I can't really take that anywhere.