^ thats what i meant to say i wanted to build the "roll bar"
sorry guys

 

I think there's some terminology confusion here.

Racing means to compete against multiple cars on track at the same time, with the winner being the first car to cross the finish line. In racing, passing is allowed at any point without any indication from the lead driver. Racing requires qualifying for a racing license, and having a car with a full, rules compliant roll cage. I don't think you actually want to go racing.

Time trials are competitions where multiple cars may be on track, but the winner is the person who posts the fastest lap time, not the first car to cross the finish line. Passing may or may not be restricted. Time trials likewise generally don't require special licenses, and while safety requirements vary, they generally don't require full roll cages.

Track days / driver's education events are non-competitive events. While multiple cars are on track simultaneously, passing is generally only allowed in designated areas with the permission of the lead car. Track days don't require special licenses, although some require convertibles to run with a roll bar.

I think what you're really asking about is track days, in which case you should be fine running a homemade roll bar as long as it passes a safety inspection. The final arbiter is always the person who reviews your car at the track or before the event, though.

Edit: Someone should write a FAQ entry about this, as at least half of the questions about "racing" on this forum end up actually being about DEs.