I've got an SC400, love it when all is good..V-8, great power no mods, SC300 less power V6, easily modified. 3 weeks ago I noticed a small crack in the PLASTIC RADIATOR!! $555.00 for a new metal one. (Of course I, & you can find cheaper ones, I got one for around $220.00) last week,my starter went (140k 0n car) $289.00 Bosch replacement, I found a reman for 150.00. NOW HERE IS WHERE YOUR DECISION STARTS.. 45mins labor to replace SC300 starter..5 FRICKEN' HOURS by a certified mech. Backyard wrenchers .."Don't even think about it!" That's about $400.00 just in labor, as opposed to $50-60.00 for the SC300. The starter is ON TOP of the engine, you cannot even see it at all until the air intake, throttle body, intake manifold, fuel injector rails, etc. are removed.
Point is, I love my SC400, but if I had to do it over, definately SC300. You will blow the $1000.00 price diff the first time something goes wrong...and those miles...Fuhgittabouit..