How many mgs of actifed or sudafed will show positive for meth in a ua?

Depends on test. Different test kits have different sensitivities, and it also depends on the amount of time between the ingestion and the test, as well as differences in individual metabolism. The test that is positive is a screening test, and should always be followed by a definitive test which can and should easily tell the difference between pseudephedrine and amphetamine.