DIY Cat Bypass
 

Anyone ever do their own cat bypass utilizing most of the existing plumbing? 86 3.2L

Not on my 911 as it came with the Euro Premuffler. I did gut a cat on a former vehicle, however.

You simply knock out the honeycomb material inside.

Interesting. Is it just basically a tube with material inside where a long rod will punch everything out?

I need to remove mine for my carb conversion, but don't want to purchase a bypass as the entire exhaust will be replaced later.

i have one for sale

its already punched out

Exactly. A crowbar works great. The honeycomb will break into pieces and then you can just fish them out.

Wear a dust mask.

I gutted mine, it is amazing how tough the material is. Large slot screw driver, crow bar, use what ever you have handy that will reach through the cat. If you plan to reuse it, remove the O2 sensor before hammering away at the guts. Dirty job, wear a mask and use a large drop sheet.

Buddy on mine's 87 removed the OEM muffler and had a exahust tip fabricated at a local muffler shop and bolted right on the Cat. The Sound is Amazing! He also added a small arm to mount to one of the Chain tensior bolts to keep the Cat and Tip up.

The wierd thing is when he punches it red embers fly out the tip, Purty Biotchen :D

I wasnt sure if that bypass was was just a hollow pipe or if it had some baffling inside.

Basic By Pass is staight thru with a O2S bung if needed.

If its just a matter of coring the cat, why do so many people by the m&k bypass?

Stock cat punched out? How much are looking to get for it?

OEM cats are very expensive with precious metals inside.

You want to keep it in case you need to smog her or at least sell it.

Some have gutted them though

It seems the going rate is about $100 for a SC CAT in the classifieds. Even cores punched out are going for $75.

So it's not a big money loss to punch one out.

In Cali "75 and earlier are exempt from smog so supply and demand here is low on those years. After 75, us political Cali prisoners have to pay the price for a good cat.

i have it posted for 75

i am selling it 75 for it i also have a vertex chip also you can have them both for $100, i am supercharging my car so i dont need......

If you punch out your own cat, make sure you get all the bits out before you bolt the muffler back up otherwise you'll end with stray pieces in the muffler that rattle around. Easy to do though.

yep its already hollowed out

Well if somebody in Cali or elsewhere wants to trade me a cat bypass for my '81 cat, I'm open! Though I have no idea how many miles or what type of shape it's in internally.

Otherwise I'm punching it out. Smog bog, I'm in Texas - we make smog for a living. ;)