hey people ... soon custum made blow off valves will be a product from ,,, nizmo 99 ,, there very good design and vent maximum flow.. wont be online for about a month or two but hey ,,, adjustable tensions ,, different trumpets or vent back tips will be available ,,, will be cheap ... its good practice ,, ill be using one for sure ,, anyway for more details ,,, either myself MENIOS or jono NIZMO99 will be glad to assist u ,,,