Exhaust help...

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Bill Frost

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I’ve got a 1999 Tahoe with the vortec 5.7. I am getting ready to do the exhaust. Thinking about doing from the motor back with an x pipe and converter delete... pros and cons? Also in the near future I will be putting a 6.0 in the truck...
 

Schurkey

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I wouldn't build an exhaust system until you figure out which engine is going to be the "Final Word".

An exhaust built to suit the 5.7 will need revisions to stuff in an LS.

Deleting the catalyst will violate Federal law.
 

Jglew82

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I wouldn't build an exhaust system until you figure out which engine is going to be the "Final Word".

An exhaust built to suit the 5.7 will need revisions to stuff in an LS.

Deleting the catalyst will violate Federal law.
+1 on this. I put 2 high flow cats on my 1990 6.0 swap. I'm getting older and don't really like the smell of exhaust that much.

You CAN do your system now, but just be aware like Schurkey said, it will need to be modified with your engine swap, so that would be a con. Also, depending on your area, most exhaust shops will not install a full system without cats if the vehicle originally came with them. They can get in big trouble for that.
 

Schurkey

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The GM "pellet-style" converters were horrible. The modern monolithics are not bad at all. GM--Ford--Chrysler are selling cars with 500+ horsepower through the catalysts.
 

L31MaxExpress

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The GM "pellet-style" converters were horrible. The modern monolithics are not bad at all. GM--Ford--Chrysler are selling cars with 500+ horsepower through the catalysts.
That they do but many of them gain 40-50 hp with long tubes and an exhaust change.
 

L31MaxExpress

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Think that's likely in this case?
Of the truck still has the stock manifolds and breathing through sthe stock head pipes it is very possible to gain 30 hp on an orherwise stock 5.7. The stock 5.7 Express vans had 3" piping after the manifolds where the lighter trucks had roughly 1 7/8" pipes kinked to about 1.5" in the bends. My Express van was one of the higher stock L31 dynos I have seen. 185 rwhp and 250 rwtq on a Mustang dyno that reads 10% lower than the Dynojet I usually run it on. It made 257 rwhp and 310 rwtq on a dynojet with the marine intake, marine cam and thorley tri-Ys into high flow cats and a walker magnaflow bus muffler with a 4" diesel tail pipe.
All 2nd gear locked converter pulls.
 
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Supercharged111

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Think that's likely in this case?

The C5 Corvettes pick up around 25whp with longtubes and 3" x pipe, but they can get that with high flow cats as they're not the holdup. The C6 Corvettes had the small diameter round canister looking cats, the wife's Envoy has them as well. I swiped a pair of 2.5" C6 cats to out on the 1509 some day, but would really prefer some 3" cats and step down to 2.5" post cat.
 
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