If you have feedback issues, put it in front of the amp. If you have noise issues, put it in the loop. If you have both, get the Decimator G.
This is the gold standard for taming noise in high-gain applications!
1 Star knocked off for the footswitch, I had to fiddle a bit recently to get it switching reliably, but it was just the actual microswitch being slightly too low, easy fix that I anticipate isn't present on all specimens.