Well I don't know or trust anyone up in that area, someone else can chime in on that...But a Real Good Port N polisher will tell you , its a ART even after 1,000's of heads done you still dont have it down like a Mad science..It takes skill an patiance to make it happen, but most Performance shops can do this for you,,,, I got mine done off line, I shipped them My head an they shipped it back! an they warranty there workmanship too......So find someone that knows there shltt, if you dont they can fuk it up for you very easy!!!!