As a basic setup for the 415 look at Marc Rheinards setup from the LRP-Masters race last year.
http://www.rczone.net/files/tamiya/t...nard_lrp04.pdf
this is where I go from for rubbertires on carpet. I just change to the hole#4 on the rear shocktower as this works better for me. This hole is the outer hole on the stock 415 shocktower. Hole #5 was drilled additionally by Marc and other guys and is on the new MS tower. But I never liked this position. For the front I sometimes go out one hole. This setup is really perfect for carpet and should work for all tracks.
For outdoors just change springs to blue or yellow front and rear maybe the shock oil to 40. Maybe you need a yellow roll bar at the front if itīs too much steering for you. But this really should work very well. I think the Tamiya cars donīt need very much setup change for different tracks. Usually I just try #2 and #3 hole at the front shock tower and different bodies as we have controltires and are limited to these. Outdoors I sometimes try different tire inserts also.
As you said now you donīt have enough steering now this is from the very hard front springs.