IMO.

if your track is more flowing/the corners are more flowing a spool would be awesome.

if you have tight layouts with 180s, ect a diff or oneway might be better.

setting up your car for a oneway can sometimes be tough and if i don't have time to figure it out i just throw in the front diff. if you hit the board a lot also a oneway or spool will always cause more damage.

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