What are the main differences, or is it like comparing a 7.5 to a Kanai? I know the Kanai and 7.5 are almost a total different buggy but what about the 777 vs. the Sp1?

It's the same difference.

a guy at a track i was running at got the reg 777 and whooped butt w/ it. and this weekend i watched a guy in a hotbodies lightning get 3rd place so its all in the pimp arm it dont matter what you wheel...

I know it is 90% driver, but I was looking for a list of differences.

Here you go. Taken from Towerhobbies.

*MP777 SP1*
TCD Front Gear Set (IFW118)
Lightweight 46T Steel Spur (IFW310)
Front and Rear Center Universals (IFW307,308)
Ventilated Steel Brake Disks (IFW122)
Hardened Upper Camber Rods F&R (IFW123,124)
Hardened Steering Rods (IFW150)
20° and 22° Hub Carriers (IFW304,305)
Special Engine Mount (IFW102)
Yellow Wheels and Wing


*MP777*
Front Planetary Diff
Standard Steel 46T Spur
Center Dogbone Shafts F&R
Aluminum Brake Disks
Threaded Metal Rods F&R
Threaded Metal Rods
20 Front Hub Carriers
Standard Alloy Engine Mount
White Wheels and Wing

edit: I think the shock towers are different too, not sure. They were very different on the MP7.5 and the Kanai 3.

Chassis? I know the SP1 is hardcoated but is the geometry any different? ex. length kick up etc?

Don't know about any dimentional differences. The SP2 is supposed to be 4mm longer.

The SP1 compares to the Standard 777 just like the K3 compares to a regular 7.5.