you'll definetly be able to tell the power difference. I really enjoy it about 2-4k rpm.
i can peel out alot easier, also.

no dyno runs. im on a tight budget saving for next project

 

awesome, thanks for the help.

 

I have another question about this set of Doug Thorley's, the fitment on them is for a 99-01, can anyone tell me if there is going to be an issue on my 03, it should be the same since its the same engine, but I don't know if they changed something in the engine compartment.

 

hmmm, good question. I wrote to them about some headers and they said for my 03 6.0L there was some fitment issues. That may or maynot still be the case. I'd call them or email them to see if that applied to the 4.8/5.3 as well. I ended up getting AZSM's.

 

They fit my engine compartment perfectly.

Heres the skinny on tri-y headers. http://www.thorleyheaders.com/tech_basics_triy.html

 

yeah, I hope they fit, I'm not sure if I can afford AZSM's, they're like $700+, the Doug Thorley's are only $435 shipped, what are my other options?

 

I would also recommend looking into the Other Guy's headers. They are absolutely top notch. They are THE only ones to extend a warranty to the supercharged crowd which tells me that they really stand behind thier headers. Even though you may not be going the blown route, that still says that they believe thiers are that much better than the others out. I haven't seen or heard much of the ones mentioned, but I know compared to the ASM's, the TOG's have thicker mating flanges and have no welds in the tubes, meaning they are all one piece of tubing.

Whatever you get, be sure and have them coated. You will not get as desirable reults from them if they aren't ceramic coated. THe coating helps keep the heat inside the header which will keep the o2 sensor hot enough to give accurate readings. Otherwise you will run rich and could possibly have o2 heater malfunction codes thrown at random.

 

if I go for TOG or ASM headers, I'm going to have to find a used set, I'm not sure I can afford $700+ headers, but we'll see, I may just have to wait longer to get them.

 

I talked to Randy at Thorley a few months ago. He said for my 04,4.8 he only had shorties (which aren't worth bothering with...small gain) . They are tapped for an EGR valve which mine does not have(don't know about 03s).
I asked if I could plug those and use TRI-Ys;he said yeah. The coated ones are about $150.00 more. They would ship direct. Don't bother with shorties. Seems like TOGs and AS&Ms are used the most,although the TRI-Ys are fairly popular. I might check-out the LaPole ones.
You might want to also consider(for whichever kind you get) if the 02 bungs are on the inside or outside...stock setup has them on the inside.

 

i'd check out the Dean LaPoles. theres a couple guys on here who have them, and i've talked to another who likes the hell out of theres.

www.pvmufflers.com
as soon as the page comes up you'll see a picture of them, along side of a power vault muffler. right under 600 bucks, ceramic coated.