M_Boats: m-15 jibs

I have a 2007 m-15 with the lapper (128%?) jib, and after a summer of sailing, I think it is too much sail for my lake with one sailor much of the time.  I am looking at buying either a regular (90%?) jib or a storm jib.  I have an old jib from another boat which is probably comparable to a large storm jib, but it is cut pretty full, is red, and doesn't look that great.  It does tame the boat right down without losing any speed.  Any opinions out there as to how much difference I would see with the 90%jib vs my current lapper and recommendations as to which way to go?