want to build custom exh with magnaflow parts for '03gt

[phurealdeaux]

i've searched and havent' really found what i'm looking for...stock '03gt throwing 0420 cel. need a new cat. while i'm there i plan on possibly doing the whole exh but, i don't want to pony up $500 for a cat back, $60 for a cat and still pay $$$ to have parts welded.... suggestions and part numbers would be appreciated...1) replace both cats and muffler and have exh built. (magnaflow part numbers if you've got em)2) replace second cat and muffler (since that's the one that seems to go out)3) just replace the cat cause there's not enough hp gain to validate the expense of the other parts...

[Raven]

Are you sure it's the cats. PO420 is a vacuum leak, exhaust leak or some other inexpensive problem 99.999% of the time. Just because it says catalyst below efficiency don't assume a cat issue.

[phurealdeaux]

hmmmm, no, not sure. every post i've read here, 0420's cure has been a new second cat.... i'll have to keep looking....

[sikvibe]

I was getting the same dtc and had to replace cat #1..I found a guy to do it for me for $200 out the door..upgrading the exhaust isnt worth the money unless your running boost or some other major modifications.

[phurealdeaux]

how did you know it was cat1 and not 2? did you pull the exhaust to check?

[phurealdeaux]

anyone know what a "heavy loaded" cat is? i've got an exhaust guy telling me i need a heavy loaded cat rather than the $60 magnaflow cat i found....

[Raven]

I would assume it means a regular (restrictive) cat not a free flow like the Magnaflow.

[TONY TAT2]

If your running thru 2 cat's,ya really dont need a muffler.

[phurealdeaux]

soooo, my car's exhaust appears to have a precat right at the exhaust manifold, an o2 sensor, another cat, another 02 sensor a resonator, some 2.25" pipe then the muffler. has anyone just cut out cat #2 and clamped in a replacement? if so, what brand, part number? anything helpful would be appreciated...