High pressure piston?

[Bojangles2169]

i was just browsing action village and came upon a "High Pressure piston".

http://www.actionvillage.com/is-bin/...UAAAD3ZtulA_2s

i just bought a tac one, and was wondering if it comes stock with one , or if the high pressure piston is a good thing to invest in?

[Coralis]

No you dont need that it is for a classic valve .... when the level 10 came out alot of classic mags would vent out the rear when a level 10 was installed and the velocity was turned up to usable levels , this was the fix for that .