Thorley Long Tubes From 99 Suburban fit on my 97 Sierra? Both 5.7

[KenKaniff]

Found some used units and just want to make absolutely sure they will fit. Thorley website no longer has the detail for our trucks.
Thx!!

 

[kennythewelder]

yes they will fit. Get as much of the ext. pipe with it as you can. The long tubes are not a direct bolt on though, and you will need to modify your original ext. pipe from the ext. manifold to after the cats. You might want to take it to a custom muffler shop and get an estimate on the install. Shorty headers are usually a direct bolt on, and will fit you original ext. pipe.

 

[KenKaniff]

yes they will fit. Get as much of the ext. pipe with it as you can. The long tubes are not a direct bolt on though, and you will need to modify your original ext. pipe from the ext. manifold to after the cats. You might want to take it to a custom muffler shop and get an estimate on the install. Shorty headers are usually a direct bolt on, and will fit you original ext. pipe.

They do bolt right up to the manifold though, right? Which gasket is the best to use?
I understand that I will need to modify the exhaust to fit the header exit and have a tune to turn off the rear 02 sensors. I did hi flo cats and dual flowmaster mufflers 6 months ago...hoping to re-use the cats at least.

 

[kennythewelder]

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Yes they will bolt rite up to the manifold, and should clear everything. I have Percy's seal 4 good on my shorty's. They are good and not to expensive. That or Copper gaskets is the only thing that will hold up.

 

[98_k1500]

Neither of these are 4x4 are they?

 

[kennythewelder]

Mine is a C 1500 so 2 wheel drive. 98_k1500 has a point about 2 wheel drive or 4 wheel drive. If you are putting headers from a 2w.d. to a 4w.d., this may be a problem. I'm not sure. The transfer case might be an issue. Other than that I think from the trans. forward should be all the same. I know that from 96 to 2001 the 5,7 are all the same.

 

[KenKaniff]

My truck is 4x4. The 99 burban they came off of is also.

 

[kennythewelder]

no reason why they won't fit then