I was thinking of creating a dual snorkel, cold air induction for my LG4 and I was wondering if this would make much of a difference to bother doing?

 

Absolutely.

When I first did my mods, I had been running an open element. Since I got it running mid-November, there were some cold mornings that the open element wasn't real friendly with while the car warmed up. I put the LG4 air cleaner on for a while, and I could tell the difference (restriction), even at part throttle.

I've got a factory-type dual snorkel on now, it's better than the open element.

You will notice a difference, but the big difference will come when you start upgrading the rest of the LG4 stuff.

Oh, when the engine was stock LG4, I ran it regularly at Bandimere. Going from the stock air cleaner to open was worth 2 tenths.

 

where is the best place to route it from?

 

The factory dual snorkel picks up right above/behind the headlights.

 

Run the tubes like this

I just stuck an open element on my 100% stock LG4, and I could notice a difference in sound and when I reved it up to 25 hundred.

 

I should run my air intake setup like that, except for the noticeable lack of two turbochargers sitting under my hood

I run an open element on my car, and am working on functional cowl induction. I remember when I had the 305 running the stock air cleaner to go through emmisions and noticed the difference immediately, in noise and throttle response. Ive never run the LG4 cleaner on my 350 though. I noticed a bit of response with my camaro (2.8 carbed) by sawing off part of the intake arm past the heat stove (yeah not too bright I know). Mostly in throttle response and slightly more top end power.

 

I made a dual snorkel aircleaner. I noticed a big seat of pants difference, but I also adjusted the air valve and switched secondary rods and hangers, so I'm not sure how much of it was just the snorkel. I'd still recommend trying it!

I wrote a tech article on that topic:
http://knightregistries.com/garage/cowl.htm