Big difference in price qtec's are around the £80 mark and yes very quiet as i have one on my fac wolverine but i am a tart and it looks nice. Saks are rimfire mods and give a sharp tinny sound on a pcp. They are also quite thick and heavy and the back end reflects lamp light quite effectively back into night vision/scopes. The stumpy's are about the best short mods available at only a few quid more than a sak and quieter. The new versions are even better as they can be extended by adding baffles or taking them away. If you go down the route of a stumpy mod make sure it is an un-proofed one as they are slightly more expensive than the proofed ones.