Thanks Dave - Looking forward to the build with great anticipation!
Your explanation on the head to header flanges makes perfect sense.. My only reason for asking is that I've had some bad experiences with divorced flanges in the past once they've gone through a few heat-cycles. Seems that the pipes get a lot of additional forces in them that want to twist and move the flanges from their intended locations. It's fine when everything is bolted up, but once removed and then subsequently re-installed, the blasted flanges are far from where they need to be to bolt up.. But thinking further - these headers had the primary tubes welded solidly to the collectors rather than slip-fit..
Keep up the fine job - you're inspiring many here!!
