Hi guys found this flow chart on a set of totally standard ls7 heads, part number 8452, that where for sale on ebay, It was flow tested at katech exhaust with out pibe.

lift intake exhaust
CFM CFM
0,2 152 112
0,3 244 151
0,4 296 190
0,5 337 209
0,55 353 214
0,6 366 218
0,65 373 221
0,7 375 224
0,75 373 226
0,8 375 227


Teh early heads had a little dip in the 0,65" flow, that is gone with the new cnc portings. And the exhaust flow is much higher with a pipe, like 270+ on the max out going gasses.
DoC