So, a little while back my 07 C2.7 kicked a check engine light for Bank 2 cat below efficiency. Yay. At the time I had just started it back up after running a short errand and was idling pointing up on a steep slope - my thought at the time was perhaps I ingested a bit of oil on the incline during warmup and it was enough to push the readings over threshold. Cleared the light and everything's been fine for a few hundred miles.
I did do a live readout on my cheapie scanner and noticed Bank2S2 was reading high after clearing the code - consistently around .15v higher than Bank1S2, which would indicate low oxygen after the cat, right? My hunch is the cat is starting to get clogged up a bit on that side and it's getting to be header time. The sensor could also be failing, but the car doesn't quite seem to be breathing right and I'm leaning toward clogged cat. It's not bad, but it revs a little slower than I'd expect, especially cold. Fuel trims are identical on both sides, so I don't think it's running rich on bank 2.
I'm unlikely to get OEM
Porsche headers
as they're not exactly the best design and are ludicrously expensive for what you get. Top contenders right now are
MagnaFlow
bolt-ins (appear to be OE spec cats, but with a slightly more optimized layout from manifold into the cat, decent price for a name brand), or the TopGear 200-cell sport
headers
at around the same cost (~1k for the pair). Bosal makes some cheap
headers
that look suspiciously close to the
MagnaFlow
units, but I'm not sold on them. Trying to balance quality and performance without going overboard on budget.
I'm tempted to go with a catback as well if I'm already going to be up in there changing
headers
out. I'm tempted to just get the
TopGear headers
and a
CircuitWerks
V2 catback, but the rational part of me worries I'm setting myself up for failure with both looking sort of like "K-Mart Brand" performance parts. What reviews I've found have been positive, at least.
Anybody want to chime in with their 2c, either on
exhaust
choices or my diag skills?
First, I would suggest that you get someone to read the sensors with a Durametric to get a good look at the fore and aft sine waves. To eliminate the possibility of a bad
O2 sensor
, swap the left to right post-cat sensors to verify their functioning. If indeed the cat is clogged, you might consider cleaning it by removing it and using a cleaning solution: YouTube is your friend.
If you decide to go for
headers
et al, be prepared to invest in a tune as well. Otherwise you may be looking at that CEL quite often. The obvious advantages are more power due to less restrictive
exhaust
flow and the tune which optimizes the hardware as well as a more aggressive
exhaust
note. The downside is $$ and stinky
exhaust
(I won't get into environmental concerns here).
I don't think, aside from the build quality, that the final performance result between the Chinese
headers
and their more expensive counterparts would be appreciable. As for high flow cats, you get what you pay for: the metals used in cats cost a lot. Happy hunting!
