Ok answers to hopefully most questions!
1. The SDW arms make the front end 4mm narrower in TOTAL, 2mm each side. They make the car a lot better to drive and give it a lot more positive steering with a spool, and indoors with a 1-way on rubbers it is unstobbale
That doesn't make the std arms obsolete, I used them the other day at Halifax (for non UK-ers this is a huge track where the last nitro euros were held) and they allowed me to run a soft, progressive setup without to much bite to scrub off corner speed. Std arms seem better on more flowing tracks, very low grip situations (the team ran std arms at the stafford national, where chris took ftd and won) or in very high grip outdoor situations, I believe this is what the Jap team run, and hence why they come on the Masami Edition.
2. The yokomo springs. As they are progressive, there is no accurate way to give them readings as the poundage varies throughout the compression. The HPI springs have ratings, but these aren't entirely accurate. A 16.9 rated HPI spring felt very similar to a 14lb rayspeed spring on the track. The best way to match the new yokomo springs is in comparison with the hpi and then rayspeed springs.
The progressive springs make the car easier to drive and smoother, but these are the comparisons and conclusions I have come to: (I also asked Chris Grainger for some clarification
) These won't be entirely spot on accurate due to the different charecterisitcs of these springs, but it is a rough guide:
yok black = hpi blue = rayspeed green
yok blue = hpi silver = rayspeed blue
yok yellow = hpi silver/pink (in between) = rayspeed yellow
yok pink = hpi pink = rayspeed white
yok green = hpi gold = rayspeed red
yok orange = hpi white = rayspeed red/grey
with a 1-way, roll bars and std arms I ran yok blues all round (halifax)
with a spool, front roll bar and SDW arms I ran yok pink fronts and yok blue rears (stafford)
These were both with 450/400 oil
As an extra note, here is something I just made (see attachment). I believed more could be done in low-grip conditions than just removing the centre top deck post, and also saw that the team did this for the last Euros (well at least Pulmper/plumper did, can't spell it!), hence I got the dremel out and set to work
old top deck is on the right hand side for comparison
**sorry attachment didn't work first time**