Cracked stock exhaust manifolds (maybe)... replace w/ shorty headers?

[mountie]

I went to an "old school" muffler shop today. I have a leak near the flange (?)...

They determined the stock manifold may be cracked, or remove / machine / replace.

Having said that, I was also planning to re-do my old stock system ( maybe an "X" pipe?)

I was wondering if I have to replace my stock manifolds, ...what's your thought of shorty headers?

1988 GMC C2500 5.7 TBI, 2-wheel drive.

 

[ima93chevyguy]

If you're thinking about redoing the exhaust it would be an excellent time.
Just make sure you get good headers and good gaskets, check for leaks, re-tighten the bolts periodically, etc.
Also you may look into long-tubes since you are redoing the exhaust and don't have to worry about it bolting right up; main advantage of shorties would be the "bolt up" application.

 

[mountie]

I am getting 2 thoughts, the expense for headers ( $ vs HP ).... I have a stock 350.,, is it worth the expense??

BUT,
If I got headers, of course I'd get good ones. ( I knew Doug Thorley )...

Shorty's would allow for the 'Y' pipe before the cat.

With a cat, ....So, after the cat, get a 1-in, 2-out muffler, an 'X' pipe then run pipes out to the right side. ( 'X' pipe after muffler???)

Just trying to get a smooth sound... Not loud.... just nice.

( My old '70 GTO was much easier )

 

[ima93chevyguy]

Long tubes will be at least 2x more expensive than shorties
"Typically" shorties are better at lower RPM and longs are better at higher RPM; so for a daily driver probably shorties.
Stock Y pipe on these trucks is highly constrictive just to throw it out there

I run a 1 in 2 out flowmaster muffler and just run them out the back behind the tires. No cat. Great sound. Not terribly loud.

 

[mountie]

I can't get a definitive answer if I can remove my '88 cat or not without issues..

I don't believe there is any computer connector to it.

 

[ima93chevyguy]

I have had no issues on my 93. No light, nothing.
Been off for 3 years.

 

[Knuckle Dragger]

I can't get a definitive answer if I can remove my '88 cat or not without issues..

I don't believe there is any computer connector to it.

Technically no, it's a federal crime to take it off.

There is no secondary O2 so the truck won't know it's gone. I run cats on everything. It's just better for the air quality and they get a worse rap then they deserve for restriction. The old pellet types sucked ass but the newer stuff flows pretty well. But to each their own.

If it were me I'd take a look at the exhaust manifold myself. Exhaust shops tend to over sell on them. in my experience new bolts and gaskets fixed most all issues. If you decide on headers don't go too cheap and use quality gaskets and hardware.

 

[mountie]

Knuckle...... The muffler shop wants to first try cleaning the surface of the stock manifolds & bolts... as they inspect for cracks. The header deal was my thought.

Either way, is it "dooable" to attach an 'X' pipe after the single-in muffler / to the dual tail pipes for sound?

 

[Knuckle Dragger]

Knuckle...... The muffler shop wants to first try cleaning the surface of the stock manifolds & bolts... as they inspect for cracks. The header deal was my thought.

Either way, is it "dooable" to attach an 'X' pipe after the single-in muffler / to the dual tail pipes for sound?

The headers are a lot more prone to leakage then manifolds. They do have some benefits but not really all that much on a stock engine. It's really up to you on what's better for your situation.

IMO, it's going to be kind of silly to "x pipe" after the muffler. I think you're talking about a y pipe to split for duels. The x pipe is a scavenging and should be right after the headers to work right. If you're set on duels out the back either come off the headers/manifolds with the cross over (not sure there is room on these trucks) then to mufflers, or y off the cat and then to mufflers and out the back. I'm sure there is much more specific info on each of these options on the site. IIRC it's prblematic because of the gas tank placement. I opted to y from the headers to the cat and 3 inch to the muffler and kick out just after the rear wheel on the left. Much like stock. I have a mildly upgraded 5.3 and it seems to work well.

A lot of this is personal choice.

 

[Roger Stephenson]

I went to an "old school" muffler shop today. I have a leak near the flange (?)...

They determined the stock manifold may be cracked, or remove / machine / replace.

Having said that, I was also planning to re-do my old stock system ( maybe an "X" pipe?)

I was wondering if I have to replace my stock manifolds, ...what's your thought of shorty headers?

1988 GMC C2500 5.7 TBI, 2-wheel drive.

I have just installed Flowtech (Holley) Ceramic Shorty Headers on my '95 K2500 350 TBI. I already had true duals with Flowmaster 40 clone mufflers with exhaust exiting below the rear bumper. There is a definite seat of the pants improvement at my normal driving speeds and if anything I think that in cabin noise from the engine is quieter. I also found that for some reason the stock exhaust had the single wire O2 sensor located in the exhaust pipe behind the area where the stock Y pipe joined. I mounted a new O2 sensor in the left hand header and used the single purple wire from the original O2 sensor to connect it. The original sensor is just used to seal the pipe now & is no longer in the circuit. I have not found anything anywhere showing an O2 sensor at that location. During the course of the header installation I also installed a new battery so the computer was off for long enough to hopefully relearn things, no codes. I have no cats on either of my trucks, an '88 c1500 and a '95 K2500; neither showed a code. I was going to go with Gibson ceramic shorty headers but they seemed to be out of stock, went with Flowtech because the cheaper painted set of Flowtechs are still good 8 years after I put them on the '88.

Sorry for the long reply.