It's also interesting that all the aftermarket header manufacturers build their headers with T3 flanges (GHL, B&B, GSF, Schnell etc), except for fabricators like Marco Menzie and Bob Holcomb. I guess all the off-the-shelf stuff are design to be as bolt-on as possible, whereas MM & BH build their headers for big HP aftermarket applications.
I agree though... for a 3.3, 0.81/0.82 A/R seems to be the best sizing for good power and response. I went with 0.78 A/R because I wanted the divided inlet turbine housing to bolt right onto the GSF headers. Divided inlet housings are suppose to offer slightly improved spool-up too, I've read.
'89 911 Turbo Cab
Protomotive MAP ECU, Twin Plugged Heads, GT2-EVO CAMs, 3.3L fully finned P&C's, ARP fasteners, C2T head gaskets, Titanium Retainers, Turbo spec valves, springs & guides, 964 splash valves, GT35R BB turbo, GSF Stainless Headers, Magnaflow Exhaust, Full bay Intercooler, TiAL 46mm w/gate, TiAL 50mm BOV, Apexi AVC-R EBC, SPEC Stage3+ Clutch kit, Crane CDI Ignition
Last edited by WydRyd; 01-11-2007 at 04:18 PM..