3" Cat-back Exhaust
Tools: MIG welder, 17mm, 14mm, 10mm -for stock exhaust, other sockets for whatever bolts used on your custom exhaust.
Materials: assorted mandrel bent 3" pipe segments (see below), 2 bolt flanges & gaskets, V-band clamp, 14" Magnaflow straight through SS muffler, exhaust hangers rods (long bolts), misc hardware.
To keep costs down initially, I ran with the stock B-pipe and exhaust. If you keep the boost low and short this is sort of tolerable. You don't want to run like that too long though because it chokes the turbo up so much you get the exhaust pulse backing up into the cylinder head, causing EGTs go up and detonation to begin. Just putting on a higher flowing exhaust can free up ~30hp over stock!
Here are the components of my exhaust. If you
look closely at the pic and start from the top left
and just follow the exhaust path you can see what parts were
needed to build it:
2 bolt 3" ID cat flange, 27" straight pipe (or stick a
resonator here), 90' bend, hanger, V-band clamp (optional), 90' bend, 45' bend ~2" segment, 9.5"
straight pipe, 45' bend, 2 bolt 3" ID flange,
another 2 bolt 3" ID flange, 45' bend, 11" straight pipe, 45' bend
~2" segment, muffler w/ hangers
(one in
front two in back), and exhaust tip angled and length to fit. If you
got these parts, you would
be pretty close
to everything needed to build a 3" cat back for a B13. 200SX and beyond
... YMMV but you shouldn't have many more
parts to buy or have left over.
Here you can see how much bigger the 3" diameter piping is compared to the puny 1 7/8" stock pipe.
The Magnaflow muffler is a smaller straight through perforated core style muffler which fits quite nicely in place of the OEM muffler. Note the new pipe follows the same route *over* the suspension and into the muffler, this is tight but can be done and gives much better ground clearance than running it booty style under the rear arm.
The stock cat is 2.5" id, however the flange of my 3" pipe bolts right up. This will work until I move on to a 3" cat and downpipe. Here is a shot of the midpipe in place, you can see the V-band clamp back there holding the two pipes together. The V-band clamp is pretty trick in that if I wanted to disconnect the muffler for some dragstrip runs or to frighten some V8s its just one minute to undo the clamp nut and disconnect the muffler.
And a shot of the rear of the car with exhaust in place. The car lost a little bottom end until the turbo starts spooling (which is now quicker so not much lag BTW) then it pulls much harder than before. Sometimes, it's actually hard not to chirp the tires at 1/4 throttle :-0 Its pretty damn loud too. Not a buzzy rice loud but a deep tone, the loudest is from 2500-4000 rpm after that it quiets down a bit. I'm going to have to put a resonator (3" Dynomax Bullet) in the midpipe, to cut droning, and Dynamat the hatch area, the noise draws too much attention for my tastes.
UPDATE: I have since put in a 21" Dynomax
Bullet muffler as a resonator in the midpipe. Ahhhhhh.... much
nicer! It got rid of the drone and
harshness as well as lowered the volume by about 1/3. If you have a street
car, put in a resonator! Your ears
and girlfriend will thank you ;-) I was able to use my el cheapo welder to
tack weld the Bullet into place (as well
as a repositioned hanger) and just take the midpipe down to the muffler shop for
the complete weld, sure beats having to
take the whole car down there, putting her on a lift, disassembly,
etc.
