SpudFiles

From McMaster in the quick exhaust valve section:

(G) Valves with Muffler— The muffler reduces noise made by the air as it exhausts. Valves are made of PBT (polybutylene terephthalate) plastic. Maximum pressure is 145 psi.

does anyone know if the muffler affects performance very much?

and this might sound like a noobish question, but on this QEV, is the third hole for the pilot on the end that isn't shown?

I would think so, look at the diagram, there arrows show how it works.
Are the letters "P", "A", and "R"? on my QEV the ports are labled "IN", "EXH", and "CYL", so I am not sure

Looks to me like there is an arrow pointing to R, and some other arrow type thing towards P, so yes, the pilot will most likely be on the unseen face.

I doubt the muffler will make much difference to performance, in the same way as it has little effect in other applications. There's a good chance it just provides somewhere for the air to expand before it enters the atmosphere, so it might increase pilot volume a little but otherwise you should be fine.

for me the port that is not visible is the exhaust port (well that's based on that schematic... AFAIK you have no idea whetheher it is a built in muffler or not... if it can be remove that's ok.. but if it's not then you have a problem... mufflers for pneumatic equipment are different than suppresors for quns - they are to slow down the air not to let it expand

Surely if that was the case, it would honk awfully or just not be a quick exhaust valve!

EDIT
http://www.pbreview.com/products/search ... ev+muffler
not everything has to make sense

Mufflers are sintered bronze/stainless steel/plastic or wire, they don't give much expansion room at all. They seem mostly to be for disrupting the air blast of the QEV and doing so is likely to cause some resistance.

Since the exhaust is in fact your barrel I'd not really want to have a muffler in the way.

agreed, as you know the normal purpose of a qev is to quickly exhaust sides of a air cylinder, the exhausting might be noisy so that would be the purpose of the muffler to damped the exhaust but in this case it dampens your firepower