Where in Seattle are you? Seattle itself, or east of Seattle?
If in Seattle, I have used Gerber Motorsport and can recommend them. If east of Seattle, Chris's German in Redmond, and Squire's Autowerk are both highly recommended by local PCA members.
squire's Autowerke in Bellevue!! Talk to Jason , the owner, he only works on Porsches. He is very fair and honest, and his prices are reasonable. A very high recommendation!