Boost question

I am running a ys trim w/ a cog setup now w/ a 75-27 tooth that's getting me 26-27lbs. spinning the blower to about 59,000. My question is, if I spin the blower at a lower rpm by changing the pulleys (say, 49,000) what kind of boost levels will I see. Looking to save on head gaskets.
Is there some kind of equation to tell the boost drop from running it at a lower rpm? Thanks-Chad

I have not stopped here for a month or 2,I can't believe a real person here.....Say I have a YSI with 28/77 cogs,At 7000 I see 26# and 1100 hp.....Impellar speed is 66412......Lets talk on "Gonedragracing.com"...PM me ...OLDHEAD

...it's been almost a year....I'll head that way!