Oh sure Johnny, but dont open them up, theyre big enough already.
d1/d2=optimum port diameter.
In other words 0.8 times the valve size, or in our case 34mm valve/27.2mm for a port dia =~80% or almost exactly 0.8 times the valve diameter and proven time and again to be the optimum for max port velocity.
Others who have had ports opened "as large as possible" or otherwise took out large amounts of material ( the bigger is better crowd) will be disappointed as the port velocity is going to stall; big ports flow slow.
Theyll be looking at a loss all round for a hole the size of the titanic's iceberg in their wallets, not to mention their dynoplots.
Ive done quite a few tests on these heads now and ive found that basically, toyota did it right, they just didnt finesse it like we can.
The total amount of material i removed to get the 202cfm figure was less than 3 grams of material taken out to get the job done.
Ill do some more tests in a while as theres a few unknowns still bothering me, so total flow may go a little higher, and its never going to be huge, but for now im pretty happy with the indicated gains.
How this will work on the 5vz ( got any port photos?) i cant say, but if its anything like the 3vzfe's ports it should respond well.