Well if its going to be an NA motor then Iron heads are better since they hold in heat better than Al... Al disipates heat too fast and will bring down the HP and Torque numbers. Of course not by much but a little... you can get the jrs in Iron too... I thought that is what StipedStangLX was planning was Iron... If I were going to buy heads again and my choices were Srs or Jrs... I would get the Srs... they flow better than the Jrs and are designed for more power than the Jrs...
up to peak torque the cylinders are being completely filled efficiantly... past PT the heads can't fill the cylinders fast enough so thats why your toque drops off.... with a better flowing head you could raise the power band a bit and still fill the cylinders, but you would lose low end torque... I am looking for more top end..
people with milder setups than mine just using different heads (AFRs or TW) make an easy 30-40 HP more than I do... so that means that my heads are holding me back... that is why I would go with a better flowing head...
just my 2 cents
Steve
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95 GTS
03 DR 650SE
Sgarzi's Machine Works
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