[94pacecarSVT]

Hey im having a muffler shop here weld on obd2 cats (thats what we have to have to pass emissions here) to a mac offroad h-pipe since i cant find a catalytic h pipe to fit mac long tubes...this will work right? since its basically the same thing as a catalytic h-pipe just custom made...

[F4iMerlin]

Unless the shop installs 4 new cats, it may fail a visual inspection if the shop knows what to look for, since the original pipe has 4.
Here is an excerpt from the EPA law concerning cats:


Generally, there are only 3 situations when you can install an aftermarket converter.
They are:
(1) if the converter is missing from the vehicle when brought in for exhaust
system repair; or
(2) if a State or local inspection program has determined the existing converter
has been lead poisoned, damaged, or otherwise needs replacement; or
(3) if the vehicle is more than 5 years old or has more than 50,000 miles*
(8 years/80,000 miles for 1995 and newer vehicles) and a legitimate need for
replacement has been established and appropriately documented (e.g., a
plugged converter or unrepairable exhaust leaks).
Any other converter replacement must be with a 'certified' or new original equipment (OE)
or equivalent converter.
Besides installing aftermarket converters only in the 3 situations outlined in response to
question (6), other requirements and restrictions also apply. These include completely documenting
the need for converter replacement, properly installing the correct one on the vehicle, and informing
the customer of his rights and certain restrictions.
Specifically, these requirements are as follows:
(1) If the replacement is not required by a State or local program, both customer and
installer must sign a statement concerning why the converter was replaced.
(Manufacturers either provide such a statement with the converter or have an
example in their catalogs.)
(2) If the replacement is required by a State or local program, the installer must keep a
copy of the statement or order by the program representative.
(3) The invoice for replacement must include the customer's name and complete address,
and the vehicle's make, model year, and mileage, as well as the reason for
replacement.
(4) Retain copies of the above invoices and statements for 6 months and the replaced
converters for 15 days (converters must be identified or marked as to which
customer's car they came from).
(5) Install the converter in the same location as the original.
(6) Install the same type of converter as the original (oxidation, 3-way, or 3-way-plusoxidation
(dual-bed)). This information is sometimes available on the emission tuneup
label or from the manufacturer's application catalog.
(7) Install the proper converter for the vehicle as determined and specified by the
converter manufacturer. There are engine size and vehicle weight limitations which
make it inappropriate to install certain converters on certain vehicles. Newer vehicles
with On-Board Diagnostic (OBD) systems may not always operate properly with
certain aftermarket products. Therefore, the catalog should always be consulted for
the correct application.
-6-
(8) The converter must always be properly connected to any existing air injection
components.
(9) Install all the other required converters the vehicle would have originally come with
unless the converter manufacturer has stated in writing that the aftermarket converter
is designed to replace more than one converter.
(10) For new aftermarket converters, the installer must fill out the warranty information
card supplied by the manufacturer and give it to the vehicle owner or operator.

Thats a lot of info, but its the law. Now, what you can do and get away with is a different story...
You should be fine as long as the new cats do not cause the MIL to come on.

[94pacecarSVT]

well. if the original pipe has four, why cant i cut them off and have them put on the aftermarket pipe?...or could i get MIL eliminators to keep the light from coming on?

[itschristorres8]

redline sells a catted mac h pipe that'll fit with long tubes

[94pacecarSVT]

can you send me the link? that would help a lot. thanks for mentioning it.

[GreenFaleen]

NC doesn't have visual inspection just obd 2

[AtlanticBlue99]

cats function better when hotter (i.e. closer to motor. even with cats, a long tube car may fail the sniffer. just put them as close to the motor as possible