Cutting? No No No...
Ya need to bring the heat. Take advantage of metals tendency to expand when it warms up.
What I do is to douse the bolt with my favorite penetrating lube (currently either PB Blaster or Gunks Liquid Wrench), then hit it with a nice long squirt with the propane torch. Make sure the flame is contacting the metal for best heat trasnfer. You can get parts to around 1,000 F if you keep the torch on it long enough. Try to warm the piece around the bolt you're trying to loosen, rather than going right for the bolt itself. After a good warm-up, quench the bolt with the penetrating oil. Lightly tapping with a wrench or hammer can help too, as previously mentioned. Rinse and repeat as necessary.
After one last heating stage, take you breaker bar, or box wrench w/BFH, or impact gun (in a perfect world) and try it. If it doesn't come off after about 5 minutes, then God Save The Queen. This has worked for me
every time I have used it so far. Just remember that heat is your friend, and propane is cheap. It's also worth mentioning that if this method is used on any critical graded fasteners (i.e.
suspension bits, lugs, brake components), the fastener should be replaced.
LIGHT IT UP BABY!!
-Steve