I've stuck an oversized Mercury output transformer into my Champ style amp and I can't get over the increase in bass response. I have been using a 10" Weber Silver Ten speaker but it almost sounds too bassy for this amp. There aren't clips around for the WGS G8C as far as I can see and guys like Weber offer a few 8" varieties as well as Jensens offerings.
I'm thinking an 8" speaker might just give the amp the "right" bass response now, the other option is to mod the amp to have less bass response. I think either options will have there charm, though someone may have travelled this path before and could advise me.
Mark
Yea, I tried going the 10" route with one of my champs, too (a early 70's silverface) ... didn't work for me and I went back with the 8"!