curious about your install of the brake proportion/bias valve. I understand the concept and use but not sure why it would be needed in AutoX? I am starting my 2nd year in FSP and just getting an idea of my own shortfalls and trying to keep car mods simple, also not running national.
If you have an early version 80mm pipe (both ends) you may have issues, not positive on that though. Wait for someone to chime in or check with the manufacturer.
Some guys don't seem to like plastic or their plastic shield fails, a handy removable cover under the filter? Looks cool when you're under the car or deflects crap better than plastic? Seriously though People seem to have issues with the stock piece in other forums and want a sturdier...
Try a small flat file from Home Depot or someplace like that, even a hack saw with some patience will work. A Dremel or die grinder with a cutting wheel will do the same but a lot quicker or you can try and find an extractor like the picture above.
Good luck in whatever you do.
If there is enough of the head sticking out use a grinder, saw or file to notch it (like a screw head) and remove it with a screw driver. Tap the hole when done or try a heli-coil, depending on bolt size.