Dan S. has posted on HC a few times on his mods, 
but he seems to want a Fender tone (?) also he states:

"I hate to modify anything, but I feel this is worthwhile:

1. The Mid control on the clean channel EQ doesn't really work so well. 
As you turn it clockwise it adds more mid-bass, but keeps an overall 
scooped response. This is caused by a capacitor across the Mid 
potentiometer. Peavey used a .015uF cap (C9) there. You could 
simply remove it, but that will result in the mid pot turning 
into more of a gain control considering its 50k ohm value. 
Instead, I recommend replacing C9 with a smaller value, 
between .003uF to .005uF.

2. The effects send & main outputs' coupling caps are too small, 
and may act as a low cut filter. This is noticeable if the unit 
is plugged into products with an input impedence below 100K ohms. 
The result is a thin sound, which is especially noticeable on 
the clean channel. To prevent this replace C40 & C30 each with 
a 1uF 400V film cap. You may be able to get by with a 250V cap, 
it all depends on the cathode voltages at each location."