it is considred an upgrade carb, yes. But it will not increase performance on the TT .46 all that much.
In the case of the TT.46 you are better off getting a replacement TT46 carb. Thunder Tiger make sa good product. Their carb tends to work very well and are not expensive. ( I have a few TT.40 pro engines used for 424 Q-500 racing and they all run very well. )
The jett carb is $75. You can purchase a TT 40 pro for about that