I had the same a few years back, all you need to do is change over to the series 2 snout then you can go as small as 54mm pulley (about 21psi using the old scale).
Change the coupler (the plastic disc between the snout shaft and the gearbox).
Ring YT for a price, the series2 snout comes with a pulley (your choice) and they deliver direct to you.
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