I just bought a Thorley tri-Y the other day. I've been reading for years on the issue and seems that the 4 into 1(LCE and TG) headers give a little more top end power were the tri-Y (which is very similar to the stock routing) is more for low end power. Also read stay under 2.5 inch pipe and you will have a good exhaust system with enough back pressure to keep some of the low end power we need so much. And I believe the LCE and Thorley are the only headers legal in CA for the first gen truck
