I am pleasantly surprised with the transmission in my 06, it is not the smoothest manual I have driven but I do not think it is worth replacing the shifter. Does anyone know if there was an upgrade over the 04 or 05?
Not sure what you mean -- but the transmission and factory shifters in all the GTOs are the same.
Seriously, the factory shifter is definitely worth replacing. The feel was best described as "a Nerf bat." It's so rubbery and flubbery.
I've got a B&M and it works great -- although a lot of people are reporting issues like leaking seals. I don't think people are installing them right -- but there are pretty smart people who have installed them and had problems.
GMM makes something called the RipShifter. Much more robust piece. Tough to install, but there are some tricks you can use that greatly simplify the process.