FWIW, I would not mod one of these unless it was a total beater and dirt cheap (which I've had and regret selling). You can't go wrong with a stock Plexi RI. Throw an SD-1 out front, maybe some NOS glass and you will never get better tones. Hell, throw a 12AT7 or 12AU7 in V1 and it will make you play better. Yes, you will have to work for it, but good playing will be rewarded.