The factory air intake hose on my 2004 G35 has some large cracks and splits. Can anyone suggest where I can get a good replacement? I've asked on a previous post about replacing the entire system with an aftermarket cold air intake kit but the feedback suggested there was not much benefit to making this mod for the money.

 

Just replace it with a Z tube.

 

^^^ what Blue Dream just said.
Z1 sells a intake for a reasonable price. Powercoated and also comes with couplers. The only issue I THINK is that u wont be able to use your stock airbox due to shorter length

 

I know concept Z performance sells a stillen Z tube that fits the factory airbox, if you really wanted to you could do what i did and replace stock intake with;
Rev-up airbox
KN high flow panel filter
Z tube
Plenum spacer.

That combo is generally regarded as the best intake setup for the G, and is really easy to install yourself.