1.Replace the .0047uf coupling capacitors in the first and second gain stage (C102 & 105) with 0.01ěf 600V caps. This will provide a slightly fuller signal range in the signal path. 
2.Replace both the 0.047ěf and 0.1ěf caps in the tone stack (C6 & 7) with 0.022ěf 600V capacitors. While the prior values are great for the “traditional” type of Fender tone, I feel the .022 caps sound better in higher gain circuits. 
3.Replace the 120K resistor in the power supply (R167) with a 100K resistor. This should raise the plate voltage in the first couple gain stages by approximately 30 volts. 
4.If it’s not already a part of your amp, install the bias control. The schematic actually lists the 5K bias potentiometer (R171) and 8.2K series resistor (R178) as “optional,” so install them if necessary. If you do so, remove the 10K bias set resistor (R158).