Four years ago I had my trans rebuilt with all the upgrades (extra clutches,valve body mods,billet converter,ect.) Trans had alight 3-4(slip or flare).Shop said I needed a chip to run the billet tripledisk converter so I got a DP tuner.Bingo flare gone for good.Converter would break the tires loose on lockup, and 3-4 shift was strong.Now four years later and14k miles on the trans,my tuner updated the tunes and the flare is back again.Tuner said to go in the trans and drill the shift plate 3-4 hole bigger.Well I find out the only thing my builder did was put in a .427 mod valve,so I install a Tugger kit and drill the holes to(.125 1-2/.109 2-3/.109 3-4)and install a Sonnex 3-4 shift valve. Trans shifts super nice now and will break the tires loose on the 1-2 shift. 2-3 is nice(I am going to drill the .125)3-4 is real nice,but alittle light under light throttle. Every 1 in 100 shifts will flare about 50 rpm.I am waiting on my .500 mod valve in hopes of a cure.It seems like the more line pressure I run,it seems to help it.The flare occurs under very light throttle only.Why?What should I look for?I hope the .500 valve wil not be too harsh during normal driving.