See I didn't have any problems with my Peco Backbox on my Mk1. When I first got my car I didn't have much money, but wanted something on a tight budget and decent "noise" (if you will).
The Peco fitted fine, and the sound was deep and also popped alot (but that's ten times better now with my cat-back Ashley system).
I gave the backbox to my mate, and its running fine on his Clio, looks ok, and sounds ok. Obviously you won't be getting power gains with it more just for the sound, etc, and I needed something to get me by. But I honestly don't see why people hate them sooooo much.
The only thing I could maybes think is off-putting is the build\durability of the stuff, but for £90 (which was how much mine was) I wasn't expecting it to be mint anyways.
So they are ok imo, but not good.