Do shorty headers add any tone and power to a stock l31 with a super 40 2 into 1 muffler?

[GmcGreenmachine97]

I have a suburban with a 2 into 1 super 40 routed with the stock tailpipe and no tips. I’m wondering if getting shorty headers will enhance the sound I already have, and if it will even have and drive ability differences. don’t want to go longtubes I like the low end power and not ready to get a cam yet.

 

[L31MaxExpress]

I have a suburban with a 2 into 1 super 40 routed with the stock tailpipe and no tips. I’m wondering if getting shorty headers will enhance the sound I already have, and if it will even have and drive ability differences. don’t want to go longtubes I like the low end power and not ready to get a cam yet.

Long tubes make more low-speed power than shorties. Years ago when the manifolds cracked, I put JBA shorties on the Express with the factory dual 3" to the muffler and factory muffler. I later discovered I had cats that were plugging up. I replaced the cats with Thunderbolt 3" metallic core cats and swapped to a Magnaflow muffler. The L31 woke up a bit. Then I found the Thorley Tri-Ys that came with head pipes to mate them to the factory exhaust piping and installed them. The difference in low-speed power was night and day from the shorties.

My 83 G20 had the factory GM shorties. I replaced them with cheap flowtech long tubes for a square body truck. Ended up regretting those cheap garbage headers not for lack of power but for thin, leaky flanges and put Thorley Tri-Ys on it. Even on a stock 305 the long tubes perked it up compared to the shorties. Those long tubes were 1-1/2" primary as well. Adding long tubes or tri-ys has torque gains similar to a small nitrous shot. 30-50 ft/lbs gains are common.

 

[GmcGreenmachine97]

Long tubes make more low-speed power than shorties. Years ago when the manifolds cracked, I put JBA shorties on the Express with the factory dual 3" to the muffler and factory muffler. I later discovered I had cats that were plugging up. I replaced the cats with Thunderbolt 3" metallic core cats and swapped to a Magnaflow muffler. The L31 woke up a bit. Then I found the Thorley Tri-Ys that came with head pipes to mate them to the factory exhaust piping and installed them. The difference in low-speed power was night and day from the shorties.

My 83 G20 had the factory GM shorties. I replaced them with cheap flowtech long tubes for a square body truck. Ended up regretting those cheap garbage headers not for lack of power but for thin, leaky flanges and put Thorley Tri-Ys on it. Even on a stock 305 the long tubes perked it up compared to the shorties. Those long tubes were 1-1/2" primary as well. Adding long tubes or tri-ys has torque gains similar to a small nitrous shot. 30-50 ft/lbs gains are common.

That’s interesting are the Tri ys complicated to instal, do you have to get a new crossover and after market cats?

 

[L31MaxExpress]

That’s interesting are the Tri ys complicated to instal, do you have to get a new crossover and after market cats?

If you can find the Thorleys, they came with it. It is hard to find any header for these L31 trucks now though.

The factory exhaust tubing and cats on the 1500s are more of a choke point than the factory manifolds.

 

[GmcGreenmachine97]

If you can find the Thorleys, they came with it. It is hard to find any header for these L31 trucks now though.

The factory exhaust tubing and cats on the 1500s are more of a choke point than the factory manifolds.

Yeah but I don’t want the clappy clap from

If you can find the Thorleys, they came with it. It is hard to find any header for these L31 trucks now though.

The factory exhaust tubing and cats on the 1500s are more of a choke point than the factory manifolds.

yeah the bends are ugly as hell but I don’t feel like deañing with the cats maybe I can just have it routed with a smoother bend and the issue would be the cat.

 

[L31MaxExpress]

Yeah but I don’t want the clappy clap from

yeah the bends are ugly as hell but I don’t feel like deañing with the cats maybe I can just have it routed with a smoother bend and the issue would be the cat.

It is the size of the tubing mainly. The OE tubing is not even 2" ID.

 

[0xDEADBEEF]

IMO, shorty headers (as an upgrade) aren't worth the time and money.

 

[L31MaxExpress]

IMO, shorty headers (as an upgrade) aren't worth the time and money.

They were definitely worth it for me as at the time I had cracked manifolds on a 60K mile L31 and Thorley was not making the Tri-Ys for the Express chassis yet. A quality set of headers withstand the heat better than the thinly cast GM garbage as well as flow noticeably better. On a 1500 though, it really does not matter power wise what is there with the restrictive stock head pipes and cats in place. On my brothers 99 Suburban we re-used the JBAs I had on the van, hooked them up to the Hooker 2-1/4" dual exhaust system they made for the GMT400s and replaced the GM cats with a set of Nissan Titan rear bullet style cats that I had that were practically new. Really woke that suburban up. The Titan rear cats flowed well enough to make ~300 rwhp on the Titan, even with the manifold cats in front of them. They were a big improvement over what GM used.

 

[0xDEADBEEF]

They were definitely worth it for me as at the time I had cracked manifolds on a 60K mile L31 and Thorley was not making the Tri-Ys for the Express chassis yet. A quality set of headers withstand the heat better than the thinly cast GM garbage as well as flow noticeably better. On a 1500 though, it really does not matter power wise what is there with the restrictive stock head pipes and cats in place. On my brothers 99 Suburban we re-used the JBAs I had on the van, hooked them up to the Hooker 2-1/4" dual exhaust system they made for the GMT400s and replaced the GM cats with a set of Nissan Titan rear bullet style cats that I had that were practically new. Really woke that suburban up. The Titan rear cats flowed well enough to make ~300 rwhp on the Titan, even with the manifold cats in front of them. They were a big improvement over what GM used.

As a repair, yes. As a performance upgrade, no.

I'm not wasting my time to remove functioning manifolds for shortys. My opinion of course.

 

[Schurkey]

Perhaps a moderator will move this thread to the Exhaust sub-forum.