still seems no one is offering any headers for the 80+ 4.7's ... what is different, anyone know? must be different bolt patters or collecter location???

 

I would guess that and the angle the collector is compared to the 07 and down

 

I would ask Nick at www.airram.com he told me the 05 and 08 4.7L blocks are the same. The only difference is the Heads. 05-07 headers will probably fit but you might have to get your down pipe modified.

 

is it benieficial to get a custom y-pipe and remove the cats?

 

I went with Spintech's high flow cats. I like having them in the event I get inspected and they perform flawlessly. I have JBA headers, custom down pipes into dual spintech cats, and true duals all the way to my dual chamber muffler. Sounds and performs awesome.

 

yeah, but things change when your FI. I'm wondering if you need the backpressure of the cats if your NA, or if you gain by deleting them.

 

I read in the Ram section that the 08+ 4.7L's have larger exhaust ports on the heads as well as a slightly different bolt pattern. The 07 and below headers won't fit. At least I'm pretty sure that's what they were talking about.

If I understand exhausts correctly (and please correct me if I'm wrong):

SC's and Turbo's need a free flowing exhaust system. Scavenging is not nearly has important. On an NA engine scavenging and exhaust pulse temp are very important. To big of a pipe diameter and you run the risk of cooling down the exhaust pulse causing them to stack up in the system. This would reduce scavenging of the cylinder(s). This is why, if you run dual 3" pipes on a 4.7L you feel a reduction in low end torque.

 

Even when not making boost, the response is great. IMHO our stock exhaust systems are way to restrictive.

On a side note, that is good info to know on the new 4.7L. I haven't gotten to play with one just yet but I want to.