Mac headers
Thread Starter
Teching In
Joined: Dec 2002
Posts: 19
Likes: 0
From: LI NY
Mac headers I currently have the Macs with the ORY and I need to install cats. Can any one give me any recomondations as far as how to and what brand. Also I have the o2 sims do I need to install the rear o2 sensors with the cats. Thanks for your help.
Launching!
Joined: Jul 2003
Posts: 249
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From: Somewhere around Detroit...
Re: Mac headers The MAC Y-Pipe with cats is probably the best choice. (Designed to fit thier headers) Although you could get a good shop to fab you up one with high flow cats too. Probably pretty costly, so I'd stick with the pre-designed one. 
Re: Mac headers Stay AWAY from the MAC cats. I don't think there is a bigger waste of money for the LS1.
Get a set of high flow cats like Carsound or Random Tech and have a good exhaust shop weld them into or near the stock locations in the MAC y-pipe. You can continue using the rear O2 simms.
You can find 2.5" high-flow Carsound cats online for about $70 each.
Get a set of high flow cats like Carsound or Random Tech and have a good exhaust shop weld them into or near the stock locations in the MAC y-pipe. You can continue using the rear O2 simms.
You can find 2.5" high-flow Carsound cats online for about $70 each.
Re: Mac headers You can just leave the simms in with cats.
Easiest thing to do is pick up a couple 2 1/2" catco or carsounds (FLP uses catco) for ~50.00 each from the mail order guys and have a muffler shop weld them in your ORP. Thats what I had done on my old ATI z28, cost me like 190.00 total.
If you can find a used MAC Y with cats cheap its even easier. The MAC cats arent all that bad, I gutted mine right at the shop and gained almost nothing on a 400rwhp car. Some claim they are horrible, maybe mac used some bad cats at one time or theirs were melted down..
Easiest thing to do is pick up a couple 2 1/2" catco or carsounds (FLP uses catco) for ~50.00 each from the mail order guys and have a muffler shop weld them in your ORP. Thats what I had done on my old ATI z28, cost me like 190.00 total.
If you can find a used MAC Y with cats cheap its even easier. The MAC cats arent all that bad, I gutted mine right at the shop and gained almost nothing on a 400rwhp car. Some claim they are horrible, maybe mac used some bad cats at one time or theirs were melted down..
TECH Senior Member
Joined: Sep 2002
Posts: 7,064
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From: Tacoma, WA
Re: Mac headers why do you need the cats on there? for visual inspection? if so it's cheaper to get the mac y-pipe with cats. after your done just switch it out to the ORP. would be cheaper than buying 2 cats and having a shop do the labor and welding to get them in a Y for you.
Thread Starter
Teching In
Joined: Dec 2002
Posts: 19
Likes: 0
From: LI NY
Re: Mac headers Thanks for all the responses. I have to install the cats for emissions. It looks like I may have to sell my baby. After my divorce my insurance went to 6700 a year. (my driving record isn't the best) 
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