RE: Club FOX!
Dammitman...
Pressure taps USUALLY work best when they're place at the widest point of the muffler. Just like 99% of the mufflers on the market...including Foxes.
Header tapping might work....might not. Why mess with it? Put the tap where it belongs and eliminate that question.
As for a larger pressure nipple? Ehhhhh....we're not dealing with much volume here, so I tend to think that a larger ID fitting would be little if any help. It wouldn't hurt to check to make sure your pressure fitting is unobstructed. Run a pin through it to make sure it's clear.
Where the needle setting is concerned? Make sure you're not pulling air bubbles/foam in the line. If you are....all bets are off, and no amount of diddling will fix it until you address the real issue. Be sure the tank is well padded, as close to the carb as is possible (this is one time where shorter IS better). Fresh fuel lines inside and outside the tank. If you've got a cheap chinese tank, throw it away and use a good tank. Hayes, GP, Tettra, Jett. Notice I didn't say Sullivan or DuBro.
Make sure you're not running too much prop. You've got to let the Q-500 wind up, and not load it down like a rented mule with a big club of a prop.
Keep us posted!!
'Race