Glasspacks

[Trenton Sauer]

I have a 1991 GMC c2500 with a 305 and I want to get glasspacks for it. There are a lot of options what are of of your guys opinions???

 

[Thatfordguy]

Thrush or cherry bomb is what most around me run. I'm not a fan of them so I don't use them personally, straight piped for me.

 

[kennythewelder]

I have a set of (2) Thrush glass packs on my 97-350. I love them. I think they are 2 1/2 and 24 inches long. They have been on the truck about 3 or 4 years. They were red, but I painted they flat black with some heat paint. People tell me my truck sounds good all the time. I think it sounds best at WOT.

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[MDR-97-Z71]

I highly recommend the Cherry Bomb Extreme muffler, close to same noise level as glasspacks but overall sounds is much better. its about $40 on summit so about the same cost as 2 glasspacks, i myself can't stand glasspacks after having them.

 

[tanman_2006]

I run a single 28" long glasspack 3" pipe y back. Sounds pretty good imo.

 

[paulson524]

I have a set of (2) Thrush glass packs on my 97-350. I love them. I think they are 2 1/2 and 24 inches long. They have been on the truck about 3 or 4 years. They were red, but I painted they flat black with some heat paint. People tell me my truck sounds good all the time. I think it sounds best at WOT.

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Did you just replace the Cats with the glass packs? Still running a muffler as well?

 

[kennythewelder]

I gutted my cats. There is nothing inside of my cats. I had to make some simulators to fool the ECM.

 

[Thatfordguy]

What did you do to make the simulators? I hate cats.

 

[kennythewelder]

Lol, I'll have to send you a link, and some pics tonight, from my lap top. I'm at work now, and don't have access to the pics, and the link on my phone. They are called mini cats, I think a company called big daddy's makes them. I just kind of copied what they have. You maybeable to Google mini cats or big daddy's and find it. I will post what I did tonight

 

[kennythewelder]

I used 4 spark plug spacers. The threads are the same as the o2 sensor threads so they fit the bung. You have to drill out 1 of the space with a 1/2 drill bit. I took some of the honey comb looking gut material that I busted out of the cats, and I ground it round to fit inside of the spark plug spacer, but only the back one. The honey comb was about 1/2 inch around maybe and about 3/4 inch long. That way the exhaust gas has to pass through the honey comb metaral to reach the rear o2 sensor, just like it would have to with the OE cat in place. Rite where the bottom yellow arrow is pointing in the first pic that says leave this one alone, is where the honey comb needs to be. The honey comb is brittle, but you can grind in down with a bench grinder, and cut it with a hack saw, but you can't pull the saw, only push the saw, because the teath will brake the honey comb if the blade bites into it. Also when you grind this stuff, it makes a lot of dust that you should not breath so use a dust mask.

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