Replacing the Pulley not a good idea?

fstrnldr

I won't pretend to have researched of the NST pulley before, but generally aftermarket "under drive" pulleys have a very bad reputation. Harmonics in an engine are a very real issue, and there are countless articles on the subject from very recent to decades past. I would do a quick google search at least, and get some of the opinions of people that build actual race engines for a living.

Having seen an oil pump shatter taking out the entire engine and turbo system as a result of an un-dampened pulley, i'll vote to keep it stock, or upgrade it to something like a fluid damper when it is needed.