Yes they will push the cats back. As far as inspections go, some places won't even pass you if you have cut and altered the stock cats AND/OR ost places won't touch cats if they are being altered from their original state. meaning you'd have to buy a replacement part like a Mag catted y-pipe if you planned on having a shop do the work. But if you can have someone you know to do all the cutting/welding of the stock cats, then you'd be good to go.
Nobody around here will even weld up a hole in a cat or even patch a hole infront of the cat. they make you buy a whole new piece.
Just letting you know what you may or may not run into.

Also, with LT's. Even if they are stainless, unless they are T-304 they will rust. Most companies use T-409 which will inhibit surface rust, plus LT headers put out ALOT of heat under the hood so if you can swing getting them ceramic coated i would go ahead and have that done. Since your in TX, you obviously get lots of heat.
Or, maybe take that ceramic coated money and buy an extractor hood.

don't forget about the 02 extenders.

 

ok well i just read that these are midlength headers. will i still have the same prob? i know about the ceramic coating was gonna get it done... and dont worry i already have a hood

 

For a y-pipe you could do the magnaflow and have a shop fab the rest or you could do a premade one like the pacesetter or JBA, each of which Moe's carries. I went with the pacesetter bc I didn't want to have to deal with any shops for the install.

The LT's will move the cats back some. The O2 wiring will be too short so you will need extensions or will have to splice the wires and make them longer.

You also need to think about what you are going to do for cats? Reuse the stockers or go high flow?

If you decide to do this project, let me know. I have a couple O2 sensor extensions laying around that I never used on my truck that I could send you. It would at least make the wiring of the front 2 O2 sensors easier for you.

 

Hey teach, most all Domestic stock cats are high flow these days. pretty sure that i seen a test review a while back on the Dodge cats and they flowed almost as much as an aftermarket high flow cat.

Midlength requires a special y-pipe. I would price eveything out with actual LT's and a Y-pipe with all expected work and do the same for the midlength set-up.

If it were me, I would go with whatever would allow a fully stainless exhaust. Midas or any muffler shop will not be able to bend stainless. they only work with mild steel.

Now, you can get prebent stainless parts and cut/weld to fabricate together, but i think that's getting over your head for costs. it would be for me anyways...lol

 

when i say fully stainless, mild steel headers that are coated inside and out are acceptable in my books. I'd take those over plain stainless TBH.

 

found this when i was reading there install instructions
The chrome plating applied to all Thorley headers is a high-nickel chrome finish applied to retard corrosion. This is a “heat” chrome to preserve the metal. This finish is not “show chrome” intended for the sake of appearance. This high-nickel chrome turns colors and approaches black as it cooks into the metal. The brilliance of the chrome finish is not cov- ered under the warranty. Contamination of the surface by foreign substances may produce other color patterns. This can be prevented by routine cleaning.

and found the gains are 27hp and 41tq

 

I was thinking high flows more for ease of fit rather than flow. That way he could order an exact fit cat for those collectors rather than trying to manipulate the stockers into fitting. IDK if bullet has a welder or not but I he goes with the stockers he will probably need to do some cutting and welding to get the stockers to fit or take it to a shop.

 

well i dont have a welder and i was gonna keep the stock cats. i shouldnt have to move them with mid lengths right?

 

Pretty sure you will still need to do some fabbing. I believe that only the shorties bolt on to the stock exhaust.

 

searched on dt and one guy who got them said the 03s are bolt in and the 04/05 are weld in... he also got the jba ypipe