Hey John,
       The Tiico can be a bit noisy.  When you floor it, it begins to moan as
it hits the power curve, like 3500 rpm.  Under normal driving, it's not bad.
The vibration issue can make all your stuff rattle in the back, but that can
be addressed.  Highway cruising, it isn't loud.  I took off the snorkel that
came with it (because it was rattling) and the intake noise level increased.
I kind of like the roar when you floor it.
       It is quieter than a glass-pack muffler, my Maverick had one long ago
and it was annoying on long trips.  That's my take, others may disagree.

Bill Marshall
85 GL Tiico AA
Bradenton FL