Spring/suspension setup for DB01 with 3racing shocks?

[mof]

Any suggestions on which springs to use with 3racings DB01 shocks? I currently have the stock ones, but they seem a bit hard for the track conditions here. I'd like something softer.

Currently I have 2-hole pistons in both front and rear shocks with Ultimate Racing 30w oil.

I tried the Tamiya red springs, and they are a lot softer, but they are a bit tight fit on the shocks. I had to force them a bit to settle in position, so just slightly larger diameter springs would perhaps be nice.

Or any other ideas for improving the setup would be appreciated (such as the mounting holes for the shocks), with or without the stock springs of the 3racing kit.