The Definitive SC400 Exhaust Guide
 

Hey guys, I'm going to jump into some exhaust work tomorrow, so I figured I'd start a thread with the SC's exhaust specs:

PM me If there's something I should add

The Stock System:
http://www.lextreme.com/pul/aaa.ht1.gif

-2 Tubular Exhaust Manifolds in 2.25" Feeding Into,
-2 Catalytic Converters,
-A (crappy) Y-Pipe,
-A ?" Single Catalytic Converter,
-A Second Y-pipe,
-2 Resonators 2.25"
-2 Mufflers in 2.25"

Aftermarket Upgrades:

Headers:
-Rush Headers
-EK Tuning
-Tex Headers
-Lextreme(in development)

Cat Back:
-Abflug (single)
-JIC bullet

Axle Back:
-Megan Axle-Back
-5zigen Mega
-Tanabe Medalion Touring
-RMM Exhaust
-Blitz Nur spec R/S
-C one

I know I barely scratched the surface, Help me add to this guys!

Personally, what I'm going to have done is to cut between both Y-Pipes, eliminating the center cat. Then have 2.25" pipes made with an X-Pipe welded in between and call it a day. I Doubt I'll get much gain by removing the resonators or mufflers.

I just did my upgrade on the exhaust just a few days ago. What I did was straight pipe the 2 front converters, and deleted the center resonator, with a straight pipe, and removed the 2 rear resonators, and kept the stock mufflers. Overall no dronning, and not too loud. I am very happy with it. Just remember to order the copper gaskets!

Just some food for thought! Will post a video if you like.

i have cut my exhaust from the o2 sensors and from there i bent and welded an exhaust with Borla Muffs and am looking to empty my cats out to straight pipe them. i am just wondering if it will throw any codes, it shouldn't but just wondering, any help would be greatly appreciated

If I had an sc400 I would upgrade it to at least 2.5" piping, run a crossover, and 2 pipes all the way back with a resonator and 2 clean offset magnaflows. but thats just me.

We are right on track with our mod schedule. :D I just finished my coilovers a week or two ago and I'm taking the car to my buddy's shop sometime this week for an estimate on exhaust. :) My semi-tentative plan is to delete the center pipe and cat and replace them with an X-pipe, then delete the resonators. Stock mufflers for now until I can save up for Nur-Specs or find another attractive option.

I've always wondered: what are those two cans coming just off the center exhaust pipe? They look like they might by sub cats, but not really.

They are just resonators to calm the exhaust note and keep the car quiet. I have always wondered if deleting that sub cat with hurt the car or throw a CEL

I dont know if it does.. I have always had my CEL bulb pulled since it stayed all the time... This was after I redid my cluster.

if you are odb1, you will probably not throw any codes for the catylitic converter.

I literally had my main o2 sensor unplugged for the longest time when I first started my turbo project and the ecu never figured out it was missing. it just thinks it hasnt "warmed up" yet. unless of course you have a cali car which has o2 heaters, i am not sure bout that.
if you throw a code, look into the spark plug defouler trick, costs like 5 bucks.

Awesome! Thank you for sharing, and caring.

I've been contemplating this now that I have my rim situation handled. Now would it make sense to run 3" from the manifold cats, delete all resonators, then run 2 1/2" from the Y to the mufflers? I am looking mostly for proformance gains above all else. I can change the exhaust notes with my muffler choice so noise won't be a deciding factor.

If you aren't adding a SC or Turbo, there's no point doing a 2.5" exhaust. You will lose power my friend. 2.25" at the most! :thumbup:

I wouldnt be so sure, I did headers with dual 2.5" and a BFI on a otherwise stock 97 SC400. I did a baseline dyno and pulled around 235 HP at the rear wheels. Pretty sure it could do nowhere near that in stock form.

Cheap good sounding exhaust for Cali cars: Cut out rear flow-thrus, weld in (literally) straight pipe between the tip and the bend where the mufflers used to be. Sounds awesome, won't affect smog, doesn't drone, but is enough to turn heads when you jump on it.

On a side note, just for fun, I pulled the whole system from primary cats and back, taped up the O2 sensors, and ran it around the alley behind the shop--it sounds GNARLY, doesn't like to idle, but doesn't throw a CEL... Still haven't figured out how to pull up the slack on the O2 sensor lines, tho...

I think the the stock mufflers are pretty good until you install and sc or turbo on your 400. All you have to do is enlarge the pipes a bit, remove all resonators, and your exhaust will sound like you have an aftermarket one. There is one problem with my setup though; I believe I'm experiencing drooning or what ever you call it. What is causing this?