Tossing factory EGT, replacing with JPI or similar

I understand that if I had a CHT, and it had a redline (I don't have one
at all, probably because the PA-24 doesn't have cowl flaps) I would need
to keep my CHT or get something certified to be a primary CHT.

Are there any rules regarding EGT? The one I have is pretty useless. It's
an analog gauge that displays only relative EGT (it's marked in 100s of
degrees F, and a thumbwheel lets you adjust the position of the indicating
needle). I'd just leave it, except it's a 2.25" instrument right where
I'd like to put the digital replacement.

--
Ben Jackson

http://www.ben.com/