Welcome to the forum, Alex. I have been shooting airguns a little more than a year. I had a Whisper Deluxe, and it has a new home now. I have three other guns that are much more accurate, repeatable, and pleasant to shoot now. There are $200 tack drivers out there, quite a few of them.
One of my three is a different class of gun, so I won't draw comparisons, but the Slavia CZ 634 and the BAM B-26 both cost less than the Whisper. Individual examples have a pretty big variance, and although my Whisper had been tuned, triggered, and had several scopes and mounts, I never got half inch groups at fifteen yards. The very first ten shot group with my new Slavia was better than any of about 30-40 test patterns with all the scopes and the mounts, the different pellets, the technique efforts, etc.
But there are others who have had better experiences, so best of luck. The Gamo scope is terrible. The GRTIII trigger will improve your Whisper a lot. If/when you replace the scope and mount, clamp it like a vise and use Loctite. The worst design feature on the gun IMHO is the aluminum extrusion riser - the rails that your mount clamps to. The stop pin will seat in a weak, thin, section of metal (the hole in the riser) and the pin(s) on my mounts just elongated that hole and slid on down the riser. Watch for that, but I can't tell you why others have succeeded where I didn't. Another suggestion, many Whisper owners put "Great Stuff" or stuff foam into the stock to reduce the thwack noise emanating from the hollow stock.
Airguns are a lot of fun, and in most ways inexpensive to shoot. Nice guns can be had for $100.
