I was thinking the same thing. 40hp must feel a lot more noticeable but I'm guessing would really drop the mpg. My pcmofnc.com upgrade feels subtle but makes the vehicle so much better than stock. Before their tuning it just felt clunky and lame - now it feels like something you actually want to drive.

 

Do you have any pictures of this set up? Also where did you get the tube from?

 

I just installed Orion headers and its at least the 32 hp they claim. probably even more for mine since the cat was partially plugged. I have magnaflow full 2.5 exhaust, this is the cat back and cat forward system with high flow cat and all full flow tubing from the headers, stock has several squish areas in the 2.5 tubing. K&N intake and jet chip. I will also remove the jet chip and do the PCM tune, . I spoke to them about the tuning and they wernt very informative at all. pretty lame getting info from them however they can adjust for the headers and any engine lights that may occur, Its likely with the headers that the front O2 sensor will show the absence of the front cat and have a check engine light under certain conditions., Great info guys thanks.

 

Class, today we learn the word header. It is an exhaust manifold of pipes joined together with one pipe at the end.

Header.


Headers..... plural.

 

smigelskijk....here is the link to the thread that has the pics of my header....https://www.hummerforums.com/forum/h...stalled-30998/
byeatts..the install of my header has not produced a engine code. As far as i know the front o2 has no idea where its plugged into besides being upstream. it doesnt know that its in a cat. its not reading the toxins that the cat is taking out. its just measuring the fuel/air ratio.
the only code i have right now is one that is a result of installing my tuned pcm by pcmforless.com. its the code for the crankshaft position sensor, which they said happens sometimes after installing the tuned pcm. i havnt gone to a dealer yet to get it taken care of.

 

The only reason vehicles have the cat in the manifold is to meet emissions quickly right after startup. New regs require that the 02 sensor meet those parameters seconds after vehicle is started from a warm condition, That will throw a light. The rear cat will meet smog after the vehicle is at operating temps.when winter arrives its possible we may get a code especially where I live at high elevations in the Sierras.