I'm trying to get everything in order while im on crutches for the next three months.

I already have a set of 762 Castings with Big Stainless valves Fully Ported and Polished with Patriot Dual Golds. Cam i will be swapping to will be a TSP 226r or 228r with close to .600 lift and most likely a TBSS Intake manifold with a Polished/Ported 90mm Throttle body. Most likely install a 100 shot of juice as well.

Will the OBX Ebay headers I have installed now have large enough primaries or should i look for bigger? I want to get the most out of this 5.3 and run it till it croaks then install a built 370.

Any help would be great.

 

I wouldn't put the OBX's on anything that I didn't plan on making 400RWHP or more. For a hot 5.3L I would go with something with a 1 3/4" primary with 3" collectors. For a 6.0L or larger motor 1 7/8 all the way.

 

sounds like i should sell these headers and start looking for some nice 1 7/8" headers then

 

I think 1-3/4" primaries would be golden in your situation if you stick with the 5.3. You're still only dealing with 325 cubic inches.

:edit
Weren't the OBX's measured out at 1-5/8" in some thread on here?

 

I think i read that also... I'm going to start looking for a better set of headers to run on the 5.3 it should last awhile yet only has 80k on it ...I will buy larger headers when i install the 370 hopefully that wont be till the end of next year.

 

I can say with 100% certainty the OBX's are 1 5/8 primaries!

 

I've seen guys use both the OBX LT headers and the stainless OBX style knockoffs on stock 5.3L trucks all the way to 500+ hp vehicles with no problems but if you want to go with bigger primaries then go for it.

With your built 370 in the future I would get rid of the obx though.

 

I might try My stainless OBX's for the first step of the build and see how it goes running true 2.5" duals with a pair of Dynomax bullets dumped, if that is not enough i have a good lead on a set of LPP Long tubes with 3" collectors.

 

In my opinion, I'd just rock what you got until you install the 370, even if they are only 1-5/8". I wouldn't think it'd be worth it to drop more coin on another set of headers that you're just gonna swap out again in a year or so, but that's just me. Guess it depends on how serious you are with building a 370 and what time frame that would truly be in.