Tc racing powerstar dome?

[Honda 250r 001]

http://cgi.ebay.com/ebaymotors/TRX-ATC-250R-TC-RACING-POWERSTAR-COOL-HEAD-DOME-85-89_W0QQcmdZViewItemQQ_trkparmsZ66Q3a2Q7c65Q3a1Q7c3 9Q3a1Q7c240Q3a1318Q7c301Q3a1Q7c293Q3a1Q7c294Q3a50Q Q_trksidZp3286Q2ec0Q2em14QQhashZitem200329334742QQ itemZ200329334742QQptZMotorsQ5fATVQ5fPartsQ5fAcces sories

are they any good? do they help any or whats the purpose?

[machwon]

No real performance gain or advantage over a regular dome. They are cut for an o-ring head gasket.

[jas250r]

i ran one one my stock bore. no problems nice not using head gasket. like machwon said no real performance gain over normal dome.