Gap pre-73 mod

Like my name says i am new to the DIY thing. I got some basic electronic skils. But normaly i take something out of the box, plug it in, and play with it.
But now i am ready to jump in the deep end.
My first project is modding 2 Gap pre's audio-shop
2 Carnhill transformers are ordered already. CA-18-VTB1148
This far i am :)
Welcome to Carnhill Transformers Limited

But my questions:
-what more can you do with the pre's? any expierience? Some guys/ girls who did it already and did it get better?

I am not afraid to experiment, so crazy or original tips are always welcome..

Thanx for the reply's.

The pre's are good indead. Worth the money and so on. But for me it's more a project of learnig about circuits and components.
I have already preamps in a lunchbox from API that costs the double than these. I just want to pimp it up to this level (or not, like i said it's a project).
So like the carnhill transformers... I want to find out what can they do, is it worth the money doing changes.
Next step is building something from fivefishaudio diy preamps , and than something from zero. But for that i have to learn some more from al the fanatics on this forum ... :)

btw: looked for the schematics, didn't find them. I will contact Bart from for these.