Boucher,
nice pics & mods done to the Holley 2bbl.
Maybe add info to the pics to help out others for the mods?
here is a good designed wastegate/downpipe that the GN guys use,improves airflow tremendously & better boost control over the stock set-up you are using.
http://www.turbobuick.com/forums/parts-sale/302552-mpe-3-s-s-custom-fender-dump.htmlFor the Regals,it is a dump pipe,because there turbo is positioned different than yours,this would be sorta the exit angle you need for your set-up.
If you add this type of DP, your turbo will spool faster because the stock adaptor makes a sharp 90 degree turn right after the turbine wheel.
You can also, port/smooth out the factory inlet turbo piece to the compressor wheel,people have seen gains by this also.
This link below shows extensive porting on the turbo also & other items, very informative.
http://www.turbobuick.com/forums/engine-tech/258301-follow-my-port-polish-project.htmlMBHD