re: exhaust 4 GTV6

[Pierre Pfeffer <pspapc@domain.elided>]

I lowered my GTV6 a couple of years ago.  I received a "test only"
notice from the DMV and learned to my chagrin the center muffler was so
thrashed the car was failed for "diluted sample".  The motor is bone
stock.  Since I had to replace the center muffler, I decided to look for
a fix that would increase flow (I think oem cat is culprit here),
increase clearance, and keep sound level close to stock.

I contacted a local muffler shop (sole proprietor, been in business
forever, great pipe bender) and he approached the problem this way:
Split the pipes in front of the cat, replace oem cat with two cats
(don't know brand, can supply if you're interested) residing side by
side in oem location, replace center muffler with straight pipe, replace
resonator with a magnaflo muffler.  This did require relocating the O2
sensor forward where it senses only the driver side bank of cylinders.

After some driving I'm pretty happy with the result.  The system is
louder than stock, but deep and rich.  It could be annoyingly intrusive
if driving extensively in lower gears (slow speed, higher revs) - but
exhaust sound disappears at freeway speed.  The twin cats hang about
3/4" lower than oem, but since they are near the front axle, I don't
think clearance there will pose a problem - certainly hasn't so far. 
The elimination of the center muffler (which is where I always high
centered the damn thing) has taken the fear out of speed bumps.  As for
performance enhancement, there is no perceived improvement, but I
wouldn't expect enough to be noticeable short of race track conditions. 
Since I TT the car, I'll have a chance to see if it helps there (alfa tt
Jan 22 and 23 at Willow Springs, email me if you're interested) - but I
strongly suspect vehicle track performancece in this instance is driver,
not vehicle limited.

I've yet to take it back for smog test, so can't say with certainty
relocation of O2 sensor a non problem - but my mechanic has car now and
says no problems he can envision on that front.  We'll see.

Happy new year to all.

Pierre

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End of alfa-digest V7 #1255
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