So of all the "good air in/bad air out" mods:

Intake
Ported heads
Muffler
Cat back exhaust
Headers

...which makes the most difference?

 

Well I did cam/lifters at the same time I did the port and polish, so I can't say for sure, but I'd say the port and polish, followed by intake, then headers/midpipe, then muffler/catback.

 

With a K&N it's bad air in, worse air out.

 

In my opinion, you start with the exhaust. Doesn't matter how much you make your engine breathe, if your exhaust is restrictive, gain is minimal.

 

doin the headers/cat delete/ and flowmaster muffler, made a difference , then the intake, its a noticable difference

 

Just thinking about this, Alex. I remember that on the header thread you had about 15 degrees difference from ambient to intake, but when you stopped it more more like 40 degrees difference. Do you think that's because it is grabbing engine bay air when you stop? Could it be the aluminum pipe right over the exhaust, too? Wondering what might be used to shield that pipe or seal the filter... and yet still look snazzy

 

I have not looked, but where is the temp sensor for the intake air? If it is at MAF sensor, then the aluminum pipe would not be affecting the air, but if it is at throttle body, I guess it could.

 

could use some insulation type stuff around it or heat resistant tape of some sort

 

Well if there's any need for it I guess exhaust wrap would work and it comes in crazy colors but it would destroy the clean look. Maybe not necessary.

Most expensive cold air intakes come with a box of some sort. Have to think on that one. I have an extra air box and air box top... And some destructive tools... Hmm.

 

It was such a quick change in temp that I'd bet money that it was because of the lack of air movement in the engine bay. When you're moving there is a lot more air coming through your grill (especially my mesh grill) so it's not really pulling what you would consider "engine bay air". So no, I don't think it has much to do with radiating heat from the engine/manifolds to the aluminum pipe, but much more to do with how much air flow there is through the engine bay.

Also, I'm almost positive that the temp is measured at the MAF because if it was measured in the throttle body the radiating heat from the engine and throttle body would throw off the readings, though I have no real evidence to back that up.