ASM claims a 22hp increase for a NA stock 5.3 and "similar" gains with a Radixed 5.3. JBA claims 12-15 for a stock NA 5.3 and "in excess of 20" for a supercharged 5.3.

It appears that headers help but the specific design is not as critical for supercharged apps as for NA.

The JBAs are 1 5/8' shorties while the ASMs appear to be 1 3/4" mid-lengths.

Has anyone dyno-tested these particular headers on a blown vehicle?

 

Do a search on this. There was a thrad on this just recently.

 

I think ASM's claims are a little aggressive, but JBA's are outlandish. Come on, 12-15 HP for "headers" (I hesitate to even call them that) that are essentially stock manifold replacements?

I'd say 5-6 HP (max) from the JBA's and 15-20 HP for the ASM's, maybe a little more if you're blown.

 

Dont waste your money on the JBA's, shorties will give you very little if anything. I would go with ASM's, Pacesetters, or TOG's. Pacesetters and ASM's are true long tube headers and will give the best results. TOG's are more like mid lengths, but they are smog and CARB approved. You can use the cats with the TOG's as well. Pacestters are the cheapest around $400 I think.

 

I love my ASM's they helped the truck alot and they still look good after a couple of oil baths.

 

Here are some numbers from my records:
---------------------------------------
07/26/01 Dynamic Autosports
Stock Trim - N/A

249 HP/ 291 ft-lbs
---------------------------------------
08/04/01 Carlsbad Raceway
Stock Trim - Motor, Full tank of gas
.........R.T. .......0.708
.........60 ft ......2.401
.........330 ft .....6.633
.........1/8 ET .....10.105
.........1/8 MPH ....71.65
.........1/4 ET .....15.595
.........1/4 MPH ....90.12
----------------------------------------
09/21/01 Dynamic Autosports
4" Intake, MAF Relocate, ASM Headers, Cut-outs open

287 HP / 315 ft-lbs
----------------------------------------
09/22/01 Carlsbad Raceway
4" Intake, MAF Relocate, ASM Headers, Cut-outs open, removed headlight - Motor, no weight redux, 1/4 tank gas
.........R.T. .......0.869
.........60 ft ......2.322
.........330 ft .....6.349
.........1/8 ET .....9.639
.........1/8 MPH ....75.29
.........1/4 ET .....14.949
.........1/4 MPH ....94.76

249/291 to 287/315 = +38 RWHP and +24 ft-lbs
15.59 @ 90.1 to 14.95 @ 94.7 = 0.66 quicker and 4.6 mph faster
While some ET cam from me discovering that manuall shift was a good thing most ET benefits were power related.

Only power mods accounting for the HP increases are the CAI/LT header/open exhaust

 

Been searching and still reading. Plenty of header threads. Lot's of opinions but tough to find numbers to back them up. Particularly difficult to find numbers that isolate the effects of the headers alone(on a supercharged vehicle).

 

I switced from shorties to ASM long tubes when I was running the S/C. Did not get any dyno #s, but I could feel a pretty good increase on the sotp meter.

 

Open exhaust! Well that removes up to 4 psi(measured at 2000 rpm) of backpressure per side(no cats- 3psi, stock catback- 1psi). Tough to compare with that factor in there.

Thanks for some numbers though.

 

Shorty headers are basically stock replacements and are therefore pointless to spend the money on. If you are gonna spend the money on headers get long tubes....the brand that I have been most impressed with to date are the Pacesetter lts. Those things are awesome.