I personally havent had a varex muffler...i simply refuse to use any X-force products anymore, they are cheap for a reason.
2 mates have have 2 1/2" dual X-faorce exhausts on V8 commodores, the mufflers fell to bits within 6 months, another mate had a dual stainless 3" exhaist on his VT2 GTS and the welds broke/cracked in two spots.
I had an X-force 3" dump on my 33 and had to modify it to fit because none of the flanges lined up and it leaked so I had to re-weld the cat flange.
So maybe the Varex is ok (it would want to be for the price) but give it another 18 months and see how the little servo goes with the heat and grime etc.
If it lasts well thats good, but I will not use one, I would still rather a propper exhaust rather than relying on a flappy valve thing.