We have the Simpson seat and it works pretty good. My son loves his "racing seat belts".

Im our Riviera, he can sit up front as there aren't any belts in the back, so he loves to go for an ice cream run in the Riv. "Haha....Mom has to sit in back!"

I have a picture at home of him wearing his helmet when we got to take "parade laps" during the lunch break at an open track event. He really thought that was cool being strapped in his "5 point harness", wearing his helmet, and "racing" with Dad.
(It was a proud Dad moment for me, too

)
Randy