no Turbo, but I did get a nice giggle out of the inquiry.
the best way to get a faster GTX is to buy a newer GTX that doesn't have the 657x engine. the GTX comes in the 720, 787, 951 and 4tech, all are considered "slow" but all would be faster & more powerful.
not sure what "mods" there might be for the 657x, although i'm sure there are some options out there from way back in the mid 90's. Free bump, maybe somebody will chime in with some simple bolt on's, perhaps a simple impeller swap might help. But any other investment into a 95 GTX will likely never be recaptured.
I'd probably suggest just ride this puppy "as is" until it eventually dies, then upgrade to a newer model. Or sell it and move into a late 90's model with more oomph...