Gutting Pup Catalytic Converters

[USRobo]

A lot has been written about removing the catalytic converters however what gains or problems are caused if only the Pup Cats are gutted? Would that provide any additional HP or throw a code, any smells?

I believe the Z06 exhaust do not have Pup Cats and they perform better. Might consider this mod if it is effective.

 

[*89x2*]

A lot has been written about removing the catalytic converters however what gains or problems are caused if only the Pup Cats are gutted? Would that provide any additional HP or throw a code, any smells?

I believe the Z06 exhaust do not have Pup Cats and they perform better. Might consider this mod if it is effective.

would it be possible to sawp over to the Z06 pipes - at least the front portions??

I know on C4's (w/ L98's) export cars did not have the "pup cats" and neither did 84 & 85's - cars I have seen run fine and the owners say they still pass emissions (w/ main cat in place still)

 

[Mike Mercury]

I believe the Z06 exhaust do not have Pup Cats and they perform better. Might consider this mod if it is effective.

read here:
http://mikemercury.home.att.net/precats.htm

 

[USRobo]

Gutting precats

Mike, thanks for the link. I see how you did it but was it worth the effort. Any additional horsepower/torque, any smells? Better sounding exhaust, did you throw any codes?

Thanks,

read here:
http://mikemercury.home.att.net/precats.htm

 

[Mike Mercury]

but was it worth the effort.

it's a free mod; so how does one determine worth ? I think it's not as much an HP mod as it is a deepening of the exhaust note.

And also, you can give AlGore an ulcer by gutting the precats. How much is that worth ????? :lol:

But one can only come to the conclusion that the pup cats do cause some restriction - just by the looks opf the material inside.

 

[Mike Mercury]

any smells? Better sounding exhaust, did you throw any codes?

I missed these.

No smells and no codes. I've been driving for 2.5 years since.

From what I've read, the pup-cats purpose is for cold startup only. They help the main cats get lit quicker. The main cats are there to do all the smog removal.

Once the main cats are up to normal operating temperature - the pup-cats could be removed (obviously not do-able) and the emission system would still be working as initially designed (until the next cold startup).

I tend to believe this, since in the past couple of years those doing this same mod have never reported any problems with codes, smells, or failures in passing a smog test. State mandated smog tests do not require you leaving the car overnight for them to perform a cold-startup exhaust test.

Some opt to cut out the pupcat altogether and weld in a piece of regular exhaust tubing. In states where the smog check includes a visual examination - you might fail the visual test before ever getting to the tailpipe or OBD2 test.

Gutting - on the other hand - keeps things looking as they should.

.

 

[USRobo]

I missed these.

No smells and no codes. I've been driving for 2.5 years since.

From what I've read, the pup-cats purpose is for cold startup only. They help the main cats get lit quicker. The main cats are there to do all the smog removal.

Once the main cats are up to normal operating temperature - the pup-cats could be removed (obviously not do-able) and the emission system would still be working as initially designed (until the next cold startup).

I tend to believe this, since in the past couple of years those doing this same mod have never reported any problems with codes, smells, or failures in passing a smog test. State mandated smog tests do not require you leaving the car overnight for them to perform a cold-startup exhaust test.

Some opt to cut out the pupcat altogether and weld in a piece of regular exhaust tubing. In states where the smog check includes a visual examination - you might fail the visual test before ever getting to the tailpipe or OBD2 test.

Gutting - on the other hand - keeps things looking as they should.

.

Thanks - That is what I wanted to know.