I lock in the king pin so the groove is just visible above the top of the steering knuckle. With the e-clip on you are pre-loading the spring just a tad if you're using the spacer length called out in the manual. The manual calls out for an aluminum spacer plus one of the plastic ones' from one of the parts tree. I believe it's 4mm combined. I'll have to measure to be sure.
On asphalt (like the Tamiya track) I don't see the need to run the car lower than 4.2mm at the front. You need some decent clearance to let the front end roll some. IMO If anyone feels the need to run 3mm on carpet adding shims below the carbon top arm is no big deal and it's super easy.
I ran my F104 V2 for 3 months straight at TQ over the winter UF1 series. The car was good and still is a good car. I only have 3 weekends with the TRF101 and it's proven itself and I have yet to scratch the surface of trying stuff. Today I tried "in-line" steering VS. "trailing". Both set ups were good! Trailing however makes the car drive easier and I did not loose pace. I was able to do my fastest lap, beating it by a 100th with trailing. So both are quick, but to me trailing feels less sensitive. Some people may like sensitive.
Also, the TRF101 like the F104 V2 is sensitive to "toe" angle. You have to run some toe-out to get the car to be stable. Some of you I notice run straight to "toe-in" and your cars behave very erratic. I run between 2.0 to 2.5 degrees of toe-out.
With the shims under the axle per the manual, how much front droop does the car have?
Also, are you using the manual suggested spacers for the upper arm screws that thread into the lower plastic arm?