Krsteen, get a race license. If you want straight line speed, then get a race license in OR and race at PIR. It has a longer straight than Pacific Raceway, and a back straight if you don't get enough on the front (but it is shorter than the front). In any event, that was how I got the speed out of my system until I stopped racing.
If that is just not to your liking, then I suggest not speeding in your own backyard, at least that is my cardinal rule. I speed some, but not around where I live or commute.
The best areas I have been on for going fast is central OR, thru Wheeler County and the counties going south from there. I have been on every road in central OR that is on the official state map. There are straights that go for 10-16 miles, if that is what you want. You still got critters to contend with, and some of it is open range so the critters could be big. Wheeler County has 1500 people in the whole county, so there are not many law enforcement personnel, and you will find similar situations in other adjacent counties. I also love this part of the world as far as just being there, more than any other area. It is beautiful country with lots of wonderful people living there. I can't seem to stay away from that part of the U.S.
Ride to The Dalles for your first day, then ride down to John Day or Dayville (there is a nice bed and breakfast there), then you can ride in many directions for days. There are routes to Hermiston, Burns, and Lakeview, all with lonesome stretches of highway. But you have to have some days to do it.
Sorry it is far away. I suggest the race license if you cannot travel to beautiful Central Oregon or just accept that you have to go the speed limit around King County, Sno. County and Pierce County. There are the Chuckanut Flats (Skagit/Whatcom Counties), but that does get radared and if you get caught, a reckless driving ticket (what you get for going way fast) will result in your license being suspended.
That race license is looking better all the time, huh?