Nice work. Guiding looks good.
The red is a great color. My only comment for improvement is you don't have much star color. That little cluster at top left is supposed to have blue stars around the orange one. You can see an example of the colors here
http://www.iceinspace.com.au/forum/s...ad.php?t=89049
Don't know pi at all but this usually happens when lum image is stretched too much before color is applied. But given you have dslr I'm not sure what advice to give.
Cheers
Chris