I installed a Celestion Blue in my Carr Mercury & the fit was so tight that I had to remove the bell cover -not pretty to look at now but it sounds good IMHO. There is an older post on TGP where others siad they were able to install a Blue in their Mercury WITH the bell cover on and i cant see how that is possbile as the baffle on this combo cannot be moved very much if at all. Whatever. My concern is that the speaker magnet is almost touching the PI tube. While there is litterally the space of a human hair separating them, i am concerned that when the amp is being played that the vibration will make them actually touch one another. 1) even if they do not touch, is the close proximity of the strong Alnico magnet to the tube detrimental to tube life? Tone?; and 2) assuming they do in fact touch, is that detrimental to tube life? Tone? I have thought of putting a slim silicone o-ring tube damper on the tube to act as a cushion b/t the tube & the magnet, but this would put the magnet & tube damper in contact 100% of the time and also slightly push the tube out of alignment in it's socket. Not a good idea?