He's rite its not just the headers add one have to be combined together to get gains for example a cai need other this to see a gain in horsepower that noticeable with bigger mas and bigger throttle body also some porting of the intake plenum same with exhaust with headers good free flowing mufflers also but it has to be rite you still need to be rite with the size as you can lose hp with the wrong set up that's where the dyno comes in but we all don't have the use of them

 

I seem to remember the "back pressure" argument, and to find the right balance of flow and pressure. I installed a CAI and the Summit Cat-Back due to my budget. I am thinking the headers are good for $200. I know,,,they're shortys, not long tubes. To answer another gentlemans question earlier, I am replaving them as manifold has some hissing and my mechanic friend told me I need to think of replacing then, and some new headers would be a viable choice.

 

Ah yes the "back pressure" argument. Read the link why I find that frustrating/humorous. It's all about what is the most limiting factor of the system, whether intake or exhaust. You can have the best scavenging system for headers, but if the rest isn't the best it doesn't matter. Same for the intake, if the MAF isn't calibrated correctly for the intake it doesn't matter. Sorry for the tangent, I just see the words back and pressure together and it makes me jump.

https://www.f150forum.com/f11/exhaus...re-myth-78102/

 

Unless you open up to 4" open exhaust you won't have a back pressure problem.

That OBX kit looks pretty sweet, it looks like it comes with two cats and bungs for o2 sensors and everything.. It's bookmarked for future reference, thanks for posting it Otto.

 

Modifying emissions in any way is from what I understand, but its one of those laws that are on the books and not strongly enforced depending on where you live. Here in Indiana no one could care less! Those look great too, curious how hard the install is?

 

I can't see the install being that bad honestly. Worst part would be getting the old manifolds off obviously, studs tend to break and have to be drilled out occasionally, so if you're not equipped for that you'd be in trouble if you had a problem. Other than that it's probably pretty easy.

Emissions laws prosecution definitely depends on the state. In Maryland we have emissions tests every 2 years where they plug into the OBD port and test for codes and inspect under the vehicle with mirrors. That's where they get you, if your truck should have 4 and you have 2 they'll fail you. Then you've got to go through and add them in and take it back to pass. That's kind of why I'm thinking I'll hollow out the smaller cats and add in the two high flows so it still shows 4 and I won't have a problem.

 

I have obx long tubes on my 2003 5.4 with no cats true dual! I could tell a good difference in power after install and sounds great to!

 

I actually have a brand new never installed obx LT header just ONE. I'll sell it pretty cheap and all u would have to do is call obx and order another if interested let me know!