I'm actually starting one of these today . . . . but you can also look on e-bay for the Doyusha one - it's the same kit (my Testor's sprues all say Doyusha). The one advanatage of the Doyusha appears to be the decal sheet - the Testor's one is very limited, and doesn't even have the emblems on it. The Doyusha has a bunch of options for race versions, apparently, but I'm not sure about the logos.
Be forewarned, they're labelled as LP500S, but they're not - appears to actually be modelled after the first Walter Wolf special LP400S.
http://cgi.ebay.com/1-12-Doyusha-Lam...1%7C240%3A1318