I asked the same question from a few "Pros" and these are the comments that I received. The Pro 5.0 has a very short and almost straight shifter handle that will make many people reach (uncomfortably) to put the car in 1st, 3rd, 5th gears as the handle is close to the dash in these gears. The Tri-ax has an adjustable heighth handle that is "raked back" more than the 5.0 and is easier to reach. The 5.0 requires that the primary rubber shift boot be cut and modified to fit. This eliminates one layer of sound deadening material between the passenger compartment and the transmission which could make for more gear noise. The Tri-ax retains both stock shift boots. The Pro 5.0 allegedly has softer (better) detent springs to guide the 2-3 shift while the Tri-ax is "rougher", particularly making the 1-2 shift.
The boot does not need to be cut and fits nicely on the Pro 5.
The pro 5 is no where near as noisy as the triax I have heard.
I believe the construction of the pro 5 is better but the angle is not adjustable unless you call putting it in a vice adjustable
The gates are much smoother from my own personal experience.
You certainly can't go wrong with either shifter. This is the second cobra I have put in the Pro 5.0
the pro 50 is awesome in every other mustang i have ever owned. i sat in my bosses with the pro 50 and it felt sloppy not like its predecesors. the tri ax is very stiff and accurate and noisy. the thing with the noise can be treated though. you take the same substance applied between the holes on the bottom that seals shift to tranny put that between the actual handle and shifter and no noise.
I had the Tri-Ax but got a Pro 5.0 now. IMO, the Pro 5.0 is a better shifter, but the handle does sit too far forward. Not something you can't get used to though, but why have to? However, you can always buy the MGW Shifter Handle and have the Pro 5.0 sit back like the Tri-Ax.
I've heard lots of success stories of putting the same silicone you put between the shifter and the transmission between the shifter and shift handle. This eliminates alot of sound. Another thing you could do is use some rubber from a bicycle inner tube and cut it up and put it in there to absorb some sound. And last but not least, when the shifter is in gear, and the stop bolts are adjusted just right, the shifter will rattle against the bolt. You could cure this by dabbing some silicone on the top of the stop bolt or on the shifter itself, but this will also eliminate that "click" sound you hear when you slam it into gear.
Just a few things you could do if you're that picky about having that stuff stay really quiet.