With how many people running straight meth with zero problems, I wouldn't be too concerned.
Keep in mind that, in the strange event of a premature ignition in the intake, the motor will ingest the fireball. As long as the throttle body is open, your chances of a meth backfire are extremely small.
I've never had meth, but I've had nitrous on multiple cars and hit some of them pretty hard. Key is just the motors ability to ingest what you're throwing at it. Unless you're looking to drowned the thing in meth, you should be fine.
