I switched to a new brand of glow plug and I started using the LC3 O.S. hot plug for my Vertex .16 offroad nitro engine. When I started using this new plug, I noticed the pull start was a bit harder to pull with this new plug. The plug is the same size as my old one. Is this extra compression a good thing? Can it cause pre-detonation? I've noticed switching over that my buggy idles forever versus the N3 Hot plug I used where it will only idle for a bit. If so, is there ways I can lessen the compression?

You always want compression thats a good indication. Pinch is a different story that when you have metal to metal contact from your piston making a stroke in a sleeve. Break-in seals your Piston and Sleeve as you move past the break-in the pinch goes away this forms compression.

a Glow plug shouldnt effect compression as far as I know but it will alter performace. Did you have a copper glow plug shim on this or prior plug?

I always used a copper glow plug shim. I had one on both plugs.

maybe its leaving extra oil in the block or you put extra oil in the block?

IIRC LC stands for Long Reach on OS plugs and the plug is longer, and goes further into the head, causing actual higher compression from less volume in the chamber.
I tried a LC4 in my Axial .28 a while back and I just tore it down before installing in my Savage, found detonation, and the plug protrudes waay too far into the button.
I won't be running that plug anymore.

Lol, I suspect an inside joke here.

hmmm he said it was the same but yea you are definitely right about the LC os standard plugs being longer than typical standard short os plugs

I do alot of crap with RC cars lol, IIRC is a must with most of my postings...
The OS 8 that I usually run in everything is maybe 1 thread shorter than an HPI plug, (people say you lose power running OS plugs) so instead of going with an R5 or R4 or whatever HPI plug, I went with the LC4 that time, IIRC that's a long reach Traxxas plug IIRC, which I shouldn't have used, but oh well, at least I saw the pitting (hopefully) before it hammered the rod and all.

Compression is good, too much es no bueno... IIRC.