Mesa Ta15 and what overdrive pedal????

Hi everyone!!!

I´m a noobie here and i´d like that you can help me about one question.
I´ve a Mesa Boogie Ta15 (what amp!!!)+ gsystem pedalboard, but i´seaching a GOOD overdrive pedal for push it a little bit.
I´m using the first channel as an overdrive channel (gain full at top bst mode,25w) and second channel as clean (tweed mode,25w).
I´d like an overdrive pedal for push a LITTLE bit the overdrive channel (top bst mode) without change his own character...only for an extra liquid o juice gain. And if it´s possible for an extra crunch channel.
At this moment i´m trying with the nova drive....but this is not what i was looking for...too synthetic for my taste...i prefer a more organic one.
Well, what can you advice me????

Thanks from Spain.

Any of the tubescreamer/od9 green overdrives or a klon

Mesa Grid Slammer.

Rockett Blue Note

The Boss SD-1 was my favorite. Combined with some high gain 12AX7s, she screamed. 8)