Adding a window/inspection hole in Quicktime or similar scattershield.
The above is for supercharged or nitrous applications. Normally aspirated is here;
https://www.sfifoundation.com/wp-content/pdfs/specs/Spec_6.1.pdf
I can’t find it now and maybe the D6 tech director told me you can have up to two holes in the can, not counting the window.
Or maybe he said no holes with the widow. Any way I know a guy who uses one hole in the bottom of the can for plate departure and another hole in the face of the bell housing so he can change base pressure.
I’m pretty sure he could do that rather than a window.
At this point before I drilled anything I’d call whatever Division tech director you have for whatever region you are in and ask him.
I was told if the can is older than 2006 or some arbitrary year they won’t even recert them.
Or maybe it was they wouldn’t put a window in it.