Adding cats to LT headers - need some expert input.

[Charlie207]

I'm close to buying the Speed Engineering LT headers & Y-pipe kit, and want to add catalytic converts to pass emissions, and not stink.

Headers & Y-pipe kit: https://speed-engineering.com/colle...erado-sierra-1-3-4-longtube-headers-2007-2013

There's not a ton of info (as far as I've seen in the last 24 hours of sort-of searching) on the best way to splice in cats., so I figured I'd ask here for how you guys have done it.

I've read that there is a minimum distance from the end of the collector to the face of the cat. substrate, to allow for effective exhaust scavenging. That doesn't seem to leave a ton of room on the driver's side for adding a cat. I see there is a drop-in set of headers w/cats from Stainless Works, but that is too rich for my blood. Their design does offer a basic template to go off of, though.

So far, these are the shortest OBD2-compliant cats. w/O2 bung that I've seen: https://performance-curve.com/3-catalytic-converter-o2-high-flow-for-late-models-federal-emissions/

Thoughts?

 

[Joseph Garcia]

If it were me, I'd take the truck to a local exhaust shop and let them tell you how to best perform the work (and, I'd let them do the work).

 

[swathdiver]

If I were adding long tube headers to mine, I would also purchase a catted Y-pipe from that manufacturer. They've already figured all that stuff out and use performance catalysts.

I see why now, that's a huge difference in price compared to Kooks, American Racing, etc.

 

[Charlie207]

If I were adding long tube headers to mine, I would also purchase a catted Y-pipe from that manufacturer. They've already figured all that stuff out and use performance catalysts.

I see why now, that's a huge difference in price compared to Kooks, American Racing, etc.

Yeah, I'm not trying to spend $2000+ dollars worth of exhaust on a car that's worth maybe 8-10k.

I do have a welder friend with a shop to lift the car up, so that's a plus, vs. my normal rolling around on a gravel driveway.

 

[swathdiver]

Yeah, I'm not trying to spend $2000+ dollars worth of exhaust on a car that's worth maybe 8-10k.

I do have a welder friend with a shop to lift the car up, so that's a plus, vs. my normal rolling around on a gravel driveway.

It may only have a market value of $8-10K but how much would it cost to replace it?

I'm slowly getting mine ready for more power, going to spend a pretty penny on a 3.5" Y-Pipe and exhaust system, about $3.5k.

How long will those headers last compared with Kooks for example? If they'll last longer than you plan to keep your truck then it makes sense.

 

[992dr]

It's been a while, but I have cut down cats for this exact reason. It's easier to adapt them with a little ingenuity.
They started out as 2.5"in/out Magnaflow spun metallic converters, and I cut them down to 3" in/out. It shortens them quite a bit for tight spaces.
Personally, I'd prefer a quality header and a fabricated y-pipe

 

[Foggy]

I looked at what Kooks stuff is now $$$$$$$
I really like my Kooks headers and catted Y pipe..
But WOW ! I bought mine before the plandemic and *****omics
They have doubled in price !!
I did the SS headers & Y.. Then had them thermal coated for
longevity . I'm very happy. I've heard horror stories about the
cheaper headers with spark plug access , quality, leaks, etc

 

[Charlie207]

I looked at what Kooks stuff is now $$$$$$$
I really like my Kooks headers and catted Y pipe..
But WOW ! I bought mine before the plandemic and *****omics
They have doubled in price !!
I did the SS headers & Y.. Then had them thermal coated for
longevity . I'm very happy. I've heard horror stories about the
cheaper headers with spark plug access , quality, leaks, etc

I'm probably going to roll the dice with Speed Engineering headers and Y-pipe. There seems to be many more positive experiences than negative.

 

[992dr]

Keep us posted when you get them.

 

[Tonyrodz]

I'm probably going to roll the dice with Speed Engineering headers and Y-pipe. There seems to be many more positive experiences than negative.

Don't use the header gaskets they send, buy your own.

 

[buckwild27]

I live in the land of rust and spent the money on 1 truck for the stainless works system front to back. It holds up.

 

[Charlie207]

Don't use the header gaskets they send, buy your own.

Good advice, for sure. I was going to use the MLS gaskets....GM or AC Delco/whatever, not the single layer junk.

 

[Charlie207]

I live in the land of rust and spent the money on 1 truck for the stainless works system front to back. It holds up.

If my rig were newer or had less rust potential I'd probably save up, but I estimate 4 years or so before it becomes a full-time job fighting the inevitable rust devils.

 

[buckwild27]

Yeah my truck got crashed into in a parked garage so it's done for. But a side note the body of a short box 1967-72 chevy C-10 fits on the tahoe chassis so the exhaust system will live on.

 

[Charlie207]

Yeah my truck got crashed into in a parked garage so it's done for. But a side note the body of a short box 1967-72 chevy C-10 fits on the tahoe chassis so the exhaust system will live on.

That's funny, I was just reading about a project like that.

https://reddit.com/comments/1lne2x2

 

[buckwild27]

That's funny, I was just reading about a project like that.

https://reddit.com/comments/1lne2x2

Yep that's the goal except I'm going 2wd and using a 6 speed manual transmission from a 2005+ Nissan Frontier and a gmt900 chassis and a 1988-98 short box stepside. Body wise this is what it will look like.

 

[Trey Hardy]

I'm probably going to roll the dice with Speed Engineering headers and Y-pipe. There seems to be many more positive experiences than negative.

I’ve had 4 sets or more on my trucks and haven’t had an issue with them at all.
Also just about every one of my friends has ran them also (atleast 6 off the top of my head) with no issues and my tuner put me onto them and can get them discounted (think my last set was like 275-300$ something.
For the money I’d buy another dozen before I spend 1000$ or more for a different set

 

[Trey Hardy]

I'm probably going to roll the dice with Speed Engineering headers and Y-pipe. There seems to be many more positive experiences than negative.

Like said below use quality MLS header gaskets and I put arp stainless bolts in BUT if I had it over again I would’ve gotten the studs for easier installation

 

[Charlie207]

Like said below use quality MLS header gaskets and I put arp stainless bolts in BUT if I had it over again I would’ve gotten the studs for easier installation

When I swapped engines last summer I installed studs.

 

[Charlie207]

Wheeeeeeeeeeeeee! (credit card goes brrrrrrrrrrrt)

I figure it's time to buy before tariffs jack these prices up.