[Has anyone had their daul exhaust exiting infront of rear wheels]

I run hush powers on my g35. I have a true duels all the way back with resonators and 1 set of cats removed. Its still is pretty loud when I'm on it but much quieter then other stuffed I've tried. At idle you can barely tell I'm modified and on the freeway it has a nice pur.

[Heat from LS1 in S30 engine bay]

Try lizard skin for a complete fix. People have had a lot of success with this. Additionally, I would go with the thicker carpet. Or even something like dynamat on top of the lizard skin. Maybe that last bit might be overkill...

[75 280z + ls1]

Does JCI sell the torque tube set up? I'm looking to install a 605hp LS motor in my 1978 280Z. I have a 4 point roll cage already but I have been told that I need a torque tube or some sort of frame rail upgrades.

 

You should research bad dog frame rails. There is tons of info on the forum about those.