A spa blower is mainly used when the air intake is fairly far from the spa. The blower helps the jet venturis to work properly with long runs of air pipe. However, the blower does not make the jets stronger it just adds more air to the stream.

If you really want more power to your jets, you need more water flow not air flow and the best solution is a higher HP pump. It is somewhat surprising that your current 2 HP pump is not sufficient for 4 jets even with 60' of pipe run. What size is your pipe? What is the filter PSI when the spa jets are running?

Another solution is a booster pump for the spa so you don't have it running all the time.