That's a pretty darn good amp, and shouldn't need much in the way of mods. I have a DC-3 112 combo and it's one of my favorite amps.
You can play around with some different tubes. I have a mix of Groove Tube "Mullard Clones", Mesa, JJ and E-H 12AX7 tubes in mine, experimenting with what brand of tube fits best in each spot to give me the tone I want.
The JJ EL-84s are good, with a little "creamier" tone than the Mesa version, and I use them in my DC-3 and my Maverick 212 combo.
One mod that is sometimes done is changing the parallel effects loop to a series loop. Haven't done that to mine.
You might pickup some more information at the Boogie Board forum,
www.grailtone.com .
And what really might blow yer kilt up would be one of the new Mesa pedals with the Graphic EQ. The EQ is one of the best features of the bigger DC Series amps.
And it wouldn't hurt to call Mesa and see if their tech support guys have any mods on file for that amp. I know they do mods at the factory on many of their other amps. Get some info on an EQ pedal while your at it.
And last but not least, be sure to download and READ the Owner's Manual. Very important to understand the function of all those controls and how they work together.
Cool amp, enjoy!
Bill