Courtesy of Fletch's Carbureted 5.0L webpage
Intake Flow @ 28" H20
.100" .200" .300" .400" .500"
GT-40P 61 128 169 195 196
GT-40 54 107 157 183 192
E7TE 59 114 144 156 156
'69 351W 52 103 149 174 183
289 50 97 127 156 165
GT-40Y 64 114 167 199 213
GT-40X 53 114 170 207 226
Exhaust Flow @ 28" H20
.100" .200" .300" .400" .500"
GT-40P 52 90 123 135 139
GT-40 47 94 119 128 128
E7TE 42 78 105 115 116
'69 351W 48 77 100 113 118
289 37 71 93 104 107
GT-40Y 52 98 128 137 134
GT-40X 50 106 139 153 161
Courtesy of FordMuscle.com
GT40P .100 .200 .300 .400 .500 .600
Intake 61 125 166 195 196 190
Exhaust 50 89 120 132 138 144
http://home.isoa.net/~mharrisj/fordhead.html
http://www.geocities.com/motorcitymustang/gt40p.html
http://www.fordmuscle.com/archives/2...s/index1.shtml
As you can see, FordMuscle.com got basically the same flow numbers as the above page.
The GT-40P kicks the GT-40 Iron's *** quite frankly.
What possibly possessed you to step and and talk about stuff you obviously don't know about? It's widely held that the GT-40P or 2nd GEN GT-40 head flows significantly better than the original GT-40.
I spent a good week researching the heads, flow numbers, and reasons for the GT-40P heads begin better. I originally thought the GT-40 heads would have been better, but I never stepped in telling people they were wrong without researching like you just did.
The GT-40P's eliminate most of the thermactor bump that chokes off exhaust flow, the ports are designed for increased flow velocity (more flow to people who don't know what that equates to), a smaller combustion chamber (increased compression about 3/4 of a point) further adding hp.
You're an idiot if you think the GT-40 outflows the P on the exhaust side between 400-500 lift. See above reference to the thermactor bump. Also see above reference to better port velocity thanks to redesigned intake and exhaust ports.
You really need to research your **** before you come in here spreading misinformation.