My experience is that you only want to buy speedmaster heads bare. All there parts are junk. They will fail. I buy the bare heads and do my own valve jobs, porting and but name brand valves, springs and machined keepers. Head castings are ok, but guides wear out fast. I have a cure for that. A number of there heads have very good port design, and with a good head porter will make as good or better power than AFR heads CNC heads. When it comes to LS heads, you are better off with a stock LS 3 or LS9 head, put your money in the porting, install 2.18 intake valves and put a bigger exhaust than a 1.6. I have a guy that makes me 1.625 and 1.63 valves , and I can get 278 cfm out the 1.625 and over 280 with the 1.630. I can get close to 380 with a 2.18 valve.(378-379 cfm, which is around 75% at high lift and 80% or better at low lifts between .100 lift and .300 lift)
Trick Flow sells a CNC ported Head for a little under $3000 a set. They have 2.200 intake and 1.6 exhaust. They claim 393 cfm intake, and 254 cfm exhaust That is only 65% exhaust to intake flow. That is not what I like to see. Want closer to 75%, or better. Giving up a little Intake flow for the better exhaust flow is a better move. Better exhaust flow helps make better low end torque, and HP. Plus the motor will make power at higher RPM, and also Power will hold on longer before the power curve falls off. Have seen on the dyno many times a head that had a little less flow on the intake (compared to other companies head) but had great exhaust flow #'s, make better torque and HP #'s( low end to mid-range), When it comes to LS Heads, I haven't seen an aftermarket head worth the money they charge, when you can take a factory casting and get it to flow just about as good as the aftermarket. So if you have a factory LS3 or LS9 head, put your money in those and you will be good. I assume most of everybody on here is driving there cars, so low end and mid-range power is what you want, unless it is a drag car

 

I disagree... if we are talking cathedral port heads, the heads from Mast and Tony Mamo are well worth the money... speedmaster would be my last choice for an aftermarket head... stock casting 243's are very good from the factory, but there is only so much you can deck them to increase compression. I think the bargain right now is the Mast heads at $750 bucks for a bare head. If you are talking rectangle port... yes factory heads are really good. but, even with a lot of work they are not going to out flow serious racing heads like MAst Mozez heads or Edelbrock LS-R castings... they are designed strictly for a straight runner profile no way is a factory casting is going to even come close to out flow them. there is a reason why guys like Kurt Uban, Billy Briggs, Nelson, BES, RED (insert favorite engine builder here) ect.... use these heads...

 

I guess I'm not clear about your post.
Are you a representative for a head manufacturer? Are you advertising your porting shop? (If so, you will need to register with the forum administrators and become a forum vendor).
You indicate some significant porting results but I wasn't sure from your comments whether you are hand porting or CNC porting the heads.
If I understand you correctly an owner can take stock castings and with work have them flow as good or better than the aftermarket heads; but custom valves, and porting are not jobs most owners do.
Perhaps you can share more info with us.