I know someone with the summit headers on their vehicle and hasn't had any problems with them yet.

I have used Edelbrock's in the past on my Chevy's though and liked them.

 

It will would be interesting to see to if there is a change if you only do the headers and leave everything else as is. Because technically it is not unmetered, the O2 sensors will detect the change (if working) in the exhaust gases and compensate. Of course the cat. has to be working also. This is a very interesting subject and I hope you give some updates.

 

Of course with the Hemi, I'm not comparing apples to apples here, but with the installation of LT headers I did not feel like I lost any low end torque, at least not enough for me to notice. I won't say I gained anything down low either but the butt dyno registers very feelable gains from about 2500 rpm and up! I kept the cats (moved 'em back about a foot and a half) and that may have helped keep a bit of backpressure for the low end. I was worried about low end losses before going to the headers but wasn't overly concerned because my next intended mod is to go toa KRC 210 cam with a custom grind specifically to boost low end torque. So I kinda felt that would more than make up for any torque loss the headers and better flow may have created. It turns out that those concerns were unfounded. Now I can't wait to have the pennies saved up for the cam, springs, retainers, pushrods & damper!!!

 

ne Actually its the shorty headers that only give a gain in the high rpm.