Actually, all depends on the application.

There are also shorties, mid-lengths, longtubes (non-equal), longtubes-equal length and stepped longtubes available for our cars... ALL have gains over stock manifolds.

Shorties - BBK, Pacesetter, Hooker - all 1-5/8" primaries - still good gains over stock manifolds - good for stock blocks+bolt-ons - not applicable to 383s, boosted, nitrous or other apps...

Mid-Lengths - Mac, AS&M - some are 1-5/8" (Mac), while some are 1-3/4" (AS&M) primaries - excellent gains over manifolds - 1-5/8" works well with stock displacement built cars (355) - 1-3/4" most gains seen with 383ci, boosted, nitrous apps... (side-note, more power is made with 1-3/4" mid-lengths on boosted apps over most longtubes)

Longtubes - Jet-Hot, Hooker, FLP/Dynatech, Kooks, Pacesetter, etc - most are 1-3/4" (I do believe you can order hookers in thier race version with 1-7/8" primaries) - Only Dynatech has velocity collectors available - some are available with specific y-pipes, most without cats (offroad) - FLPs have a velocity merge on the Y and came with both offroad pipes as well as cats - Believe only the hooker race 1-7/8" are equal-length, rest are unequal length (someone can chime in if this is inaccurate)... Only the 1-7/8" will have an advantage over 1-3/4" midlengths for boosted apps, and works excellent for heavy nitrous use as well...

Stepped Longtubes - Not sure of make - stepped from 1-7/8" to 1-3/4" primaries - Best design for nitrous applications - Also has an advantage over 1-3/4" midlengths in boosted apps...

Biggest advantage longtubes have is the ability to scavange exhaust gases, thus increasing efficiency within certain rpm ranges... Biggest disadvantage of shorties over midlengths or longtubes is stubbed/short collectors... Midlengths are better, but longtubes have proper sized/length collectors if designed properly...

There is a ground clearence loss with ALL longtubes (as the chassis was never designed for an exhaust pipe under the drivers floorpan)... No clearence loss with shorties or mid-lengths...

Dual-cats in longtubes or some midlengths (AS&M) are higher-flowing than a big single cat on shorties/midlengths...

 

I may add the dual-cat shorties that are available are for 96-97 cars that originally came with dual-cats. The location of those cats suck for a number of reasons (such as heat, spark plug access, having to keep the stock y-pipe, etc), which means the headers suck even worse in regards to fit and being able to work on the motor comapred to the stock manifolds... You do get a gain, but woudl be better off buying longtubes with cats or AS&M midlengths with a dual-cat y-pipe...

 

Thanks for the informative post 95TA

 

Yes, changing plugs sucks with the SLP shorties. The stock dual cat y-pipe is actually pretty good flowing. The cat location on the driver's side does get in the way.

Is nobody making 1.75" shorties anymore? I know mine are and I thought AS&M was but those didn't sell that well because of the tubes everywhere. As I recall, they were worse than manifolds when changing plugs.

As far as long tubes, the only available back then was the Hooker's. They hung way too low, at the time, and weren't going to let me pass emissions. If I was to do it now, over a decade later, I'd pony up for some long tubes with cats. Might not pass a visual, but it would pass a tailpipe or treadmill emissions test.

 

I have as&m headers with rk sport iffroad y pipe. So you dont have to run cats with them.

Changing plugs is a lot easier than stock w them too.

 

I ran the old Edelbrock shorty headers a few years ago with pretty good results. They were cheap and longtubes werent really available at the time. I did the heads and changed my exhaust and picked up .4 and 5 mph in the 1/8th, so saying shorties dont work is just a little off. That being said, run the LT's if possible!

 

I may add, I have installed Macs, AS&Ms, SLPs (both types), Hookers (3 types), Jet-Hots, FLPs, Pacesetter shorty and longtubes, Edelbrocks, BBK and even a set of Kooks...

On my own cars, on the supercharged 383 in the T/A it is AS&M mid-lengths with a cat-pipe. On the Z28 convertible it is FLP longtubes with both cat-pipes and cats (gotta love the v-flanges). On my other T/A it was Edelbrocks.

The plug access on most headers really comes down to having the right tools (in most cases a shorty spark plug socket)... The absoloute BEST plug access is the Mac headers. All plugs in/out from the top without issue. There are some that REALLY suck, those would by the SLPs and a couple others that are damn near impossible to get plug access to or the keep the plug wires from burning...

 

+1, If you can swap the headers, then you can do it again even faster the second time I learned.

 

im pretty sure my edelbrocks are 1 3/4

 

AS&M are mids, and very long mids at that, not shorties..

 

The dual cat headers were shorties. They went higher than the valve covers and then back down. At least from what I remember, they were terrible looking.

 

Guess they made 2 different sets, but the ones they sell now, and rk sport which are copies of them are mids. an probably the longest mids out there.

 

Probably so. This was back in the 90's. I'm sure some things have changed

SLP mids for single cat cars were pretty nice headers back then. My parent's have them on both Comp TA's.

 

SLP 1-3/4 mids are good headers too IMO.

 

Edelbrock's utilize a 1-5/8" primary.