I bypassed my smog without a pulley and have no issues. There is a specific belt AND idler pulley you use and it works flawlessly. There will be enough tension on the belt without it squeaking! I'll get part numbers for you tomorrow. It's a b**ch getting the belt on, but it works nicely.
All the folks I've ever seen get the smog delete pulleys have had them only last a couple years before the bearings wear out.