OilHead, yes I have tested about all the saws I can get my hands on. From what I have found, if the carb makers are paying any attention at all to the pop-off pressure on their carbs for stock saws, they must be on a secret mission to conceal their knowledge...ie, the pop-off pressures are all over the board. A 242xp that I tested today, had a pop-off pressure of 34psi! More often than not, I'm finding stock pressures above 20psi. Don't know if you saw the email I posted from Walbro on the subject.... Basicly, a
guy there said it doesn't matter on stock equipment, but did go on to say that in racing engines, like in karting, the pop-off is more critical. I guess that they think it is out of their jurisdiction to have to respond informatively to any question that goes beyond stock engine requirements. Unfortunately, they act totally vague on the subject. I still haven't exactly settled on what I find is best for my modded saws, but I doubt it is 34psi.
After installing the Wojo front cover on the 036 that had already been walkerized thus making it a total of 3 5/8" exits only had to turn the H screw 1/16 to 1/8 turn richer in order to drop the 600 rpm gain that was noticed. Idle quality is excellent . It still returns to idle immediatly & spools up quick something that you would never be able to do with a factory build carb with the pop off set so high. Anyway rather than have the muffler lookin like two hoes in an abortion clinic take a chrome 3/4" deep socket & make a 30 degree backside cut keep it short & point it towards the starter side . Place that over the 2 holes you have now & wire feed weld it on. Slot out the space between the 2 drilled holes. I went the Wojo route because of the need to have screens . In addition to what he supplys I rolled up a finer mesh screen from a 066 & stuffed that inside . One other thing I've noticed about this mod is were gonna have to bring more gas. 
