The two tabs on each side are to help with cork gaskets from shifting forward or backwards as you install.
I've always found them to be culprit for leaking at the corners, but I'm also not a fan of using only RTV. When I pulled the last iron intake, it had about a year worth of use on it.
When I pulled it, I noticed an odd pattern that the silicone had running through it, almost like woodgrain at the mating surface where the intake sat. I'm not sure what caused it, but I'm wondering now, if the silicone didn't cure quick enough for use. It sat a a day before it was used.
I put a really even bead on the front and rear deck after installing the gaskets and got leaking here and there.
I think the reason Edelbrock suggests silicone is because of the crush issue with a common cork gasket. I've seen people break intake manifolds, trying to get those to crush on install, so I understand that. Mopar Performance supplies a soft foam gasket for the front and rear that I use, along with RTV to lock the oil out of the gasket on the inside and in the corners.
I trimmed the head gasket tabs with a triangle file, moving out, away from the oil galley with a shop towel behind it in the galley, took the towel out and vacuumed the area, just to be safe.
When you put the intake on, just go slow and try to straight down to keep from shifting it much.
One thing you may try with only silicone, is to set the intake on to the bead, with a thin coat on the front and rear of the intake to maybe help prevent the condition I was seeing, so the RTV bonds to itself, then start the bolts, but don't tighten them for at least a day. That way, the silicone will have elasticity and squish a few thousandths and help promote seal.
Also, do yourself a favor and run a little RTV on the threads as well as under the head/ washer of the bolt, so you don't get oil wicking up the bolt threads from the oil galley. All the LA intake bolts are the same. They are a 3/8" -16 pitch thread x 2". The threads don't start until about 1/4" into the head. The intake plenum gaskets should have an index that goes into 4 of the holes (2 on each side) to keep the gaskets centered.
