I have the MSD universal lengths too. It is close routed around the passenger side hump on the header but it does not touch. I had protecting boots on them but I did not like the way they look so I took them completley off and the last passenger side plug wire goes around the hump without thouching anything but its still about 3-4mm from the header but I guess its ok.

 

I have stock AC delco wires. The one that goes around the hump is a longer wire from an 8.1L. I used some Mr. Gasket thermal heat sleeving that I got from (EBAY) . The sleeving is small and can't be installed over the boots, so it's not an easy slip over install, but it looks good once on the wires. Can't really even tell its on there other than the wires now look red.

 

I'd use a couple of boots if you're using stock length wires. I had two wires go bad after cooking through only one heat boot. I now have 3 boots on that wire and haven't had any other issues.

Aside from that, easiest and best set of headers I've ever installed on anything.

 

what is the collector size of these headers? I looked at them and for the 4.8/5.3L it says that the primaries are 1 3/4 and 2.5 collectors for the 6.0L the primaries are 1 1/2 and probably 2.5" collectors.

Are pacesetters the only headers with a 3" collector?

 

1.75 primaries with 2.5" collector for the OBX ones I got, and they were labeled for 6.0 Hummers and 6.0L Silverado SS. I've never seen a 1.5" primary on any fitment of LSx based truck.

 

Wow, thanks so much for the replies guys, you have been more than helpful.
First time posting here (usually over at GMFS) and its been great thanks...... I am gonna try and use my stock wires and use the wrap like suggested.

 

It's on ebay right now. It looks like a new picture too. I just searched "obx" and "6.0L" and that's what came up. I thought it was odd too that the primaries would be 1.5". The smallest i've heard of is 1 5/8, but those were for shorties

 

So are the 5.3/4.8 OBXs 1-3/4 primarys with 2-1/2 collectors?

Isn't that big for a stock cam 5.3?

Or are the OBXs desinged for a modded motor?

 

what if any fitment issues are you having with the obx lt's and the y pipe on 4x4 pickups