I know that the topic of delivery valves has been discussed many times on this forum, but my area of interest lies in the delivery valve holder. Is there anyone who may point me in a direction or vendor who has experience in these upgrades. I recently exchanged the holders in my 94 with 181's, but I retained the 131 delivery valve because it had less shoulder material. I have heard of machining the bore of the holder, and also running a larger say "0. 093 holder, any information on this topic would be greatly appreciated.