GMstrong

LPP,Pacesetter,OBX.

I have heard from alot of people with the NNBS saying the the stock muffler actually flows good for stock,The 6.2 is a hell of a motor from what ive seen.

you should be happy running a 13.5 in that tank.My obs 2500 weighs 4650lbs without me in it.And BTW my results were on my trucks which is a 2000 OBS and a 99 5.3L.Im not sure how the NNBS react to longtubes.should have posted that before.

No way headers alone give you that much more HP, thats almost funny. On stock motors headers do nothing for HP and may hurt HP numbers. I guess because the exhaust is louder must mean instant HP increase. People need to stop reading the box the aftermarket parts come in. Hell if I went out and bought a performance air filter,headers exhaust, performance muffler, CAI I should see about another 200 HP according to the info on all the boxes I love when people put high flow cats on there exhaust, all cats are high flow from the factory where the vehicle is made.. to each their own,i can back up post 100%.

So i wont feel a gain switching from these http://www.classicindustries.com/images/productimg/e/emsb12r.jpg to these http://www.hawkinsspeedshop.com/exhaust-headers/images/401-911201pdynatech3.jpg... I noticed a night and day difference on my vortec 350 ATLEAST a 25hp+ gain before the custom tune.On another forum i also go on the same setup same motor without a tune put down 260hp and 324ftlbs.No i said get a tune because the stock one leaves a lot on the table,I wouldnt retune for headers.Now with that being said the LS motors have shorty headers stock pretty much so yes switching to short tube headers will not gain anything but longtubes def will.

a tune isnt need for longtubes,but with a tune youll see even a bigger gain.If you do this setup longtubes,ORY=offroad ypipe,highflow cat or no cat with a spintech muffler dumped,and K&n filter without a tune you should see an easy 25hp to the wheels thats about 40hp to the flywheel and with a tune depending on which company tunes it 35hp to the flywheel maybe even more.Plus a TR220 cam you got yourself a fun truck.

I agree on the injector cleaner,Also how long ago did you do plugs and wires?Clean the MAF,Thorttle body out too.