Those Tower/GMS mufflers are built with a similar principle to Helmholtz resonators or 1/4 wave pipes. The Tower mufflers are shorter than the red Jett mufflers, but without any baffles. I'd think the tuned range is a bit higher in the rpm band, but would probably still add a bit more kick to a bigger prop.
My GMS .47 on the red Jett muffler really howled on a 10x6 - turned 500rpm better than my TT Pro .46. I wish I had a tower muffler to compare to the red Jett muffler. My GMS .47 didn't come with the muffler.
In case anyone has any interest, Dub Jett has some informational videos on YouTube now. Tuning tuned pipes and setting carb's. Search Jett Aerotech on YouTube.