Performance Exhaust Options for the Cadillac Northstar

1996 Stock Exhaust:  2.5 inch piping back from the catalytic converter to a resonator (high flow muffler).  2.5 inch piping from the resonator to the Y-pipe which splits the flow for the dual mufflers.  2 inch piping from the Y-pipe back to each muffler.  Mufflers are offset in, center out.  Muffler cases are 20 inches long, 11 inches wide, 5 inches tall.  2 inch piping out from each muffler to dual tips. 

Sound File this sound file was taken with a Kodak DX3600 camera.  The sound file is of the car starting (the clicks/clunks) then idling (almost inaudible), and finally revving to 6000 rpm or so.

1998 and after:


Pre-98 cars:

  • Borla STS and Eldorado Cat-back $1109 (out of production)

  • HKS STS Cat-back $690  TM Engineering  $690, plus adapter for 94/95 cars.

Any Car: Replace mufflers only.  Options:

Dynomax stainless steel universal mufflers 

Ultra Flow Universal Applications
Try two Model 17285 Ultra Flow Stainless Steel (SS): 2" in/2"out, with 20" shell, 4 1/4 x 9 3/4 body, which appears to match my 96 STS measurements above. 323 CFM of flow alone, 646 CFM for two.  

 Model 17283 Ultra Flow SS 2.5"/2.5" for 489 CFM alone, 978 CFM with two.  To find the DynoMax performance exhaust dealer or service outlet nearest you, call toll free 1-800-767-DYNO.
See GTP installation



  • Chrome or gold exhaust tips -- Protrim

  • 2001 Aurora Corsa System:


What have people actually done?  Exhaust survey:

LEIF I have a 1993 Allante and lives in Sweden. I have installed dual Borlas for Corvette. Both the look and sound  are really impressive.
Robert   2.5"/2.5" Y pipe, 2.5" Dynomax Super Turbo Mufflers

I upgraded the pipe between the resonator and the "Y" pipe to 3".  The "Y" pipe was upgraded to 2.5" and I installed 2 Dynomax Super Turbo Flow Mufflers (Part#  17733) that are 2.5"  in the pipes that go through them.  The entire custom system cost $266 installed.  That is parts labor and tax all together.
The Car has a very smooth deep tone.  It has been compared to a Ferrari sound only deeper.  I am very happy and would not go with any other mufflers.

I didn't notice performance increases until I installed my K&N Cone.  I removed the factory air box entirely, I removed that air intake resonator underneath it entirely, and I cut the corner off of that shield on the bottom of the car so you can look straight down from the top and see the ground.  It can get all the cold ait it wants.  I know your site says to cut holes in that air resonator piece but why bother.  Removing it completely, does a much better job, and when I trade the car I can put it back on and no one ever knows anything was done.

I installed a 7" K&N Cone.  It is K&N part # RU2590.  It is bigger and
longer than the one that Luke sent you pictures of.  In my opinion it is the perfect cone for 98-02 Cadillacs.  It is the biggest cone that will fit in that space and still fit, although it will be snug.  It cost me $53.

I used to race a heavily modified 97 supercharged Rivera owned by Dustin.  My SLS always lost by 2 car lengths in the 1/4 mile when we would street race them.  After my exhaust and K&N cone modifications, I beat his Riv by 2 car lengths in the 1/4 mile.  Including the length of his car that is a 5 car length performance increase for a about $320.  Best bang for the buck.  I don't know what all this means in #'s but I hope to get to a track and find out.  Luke, Dustin, and I estimate that it is around a 14.5 in the 1/4,
but that is only a guess.
My exhaust still isn't too loud.  Just another notch higher on the radio and you don't even hear it.  It sounds great under full throttle and when you are going 30mph and stomp it so it gears down it sometimes chirps the tires.
I used the Dynomax Super Turbo Flow (aluminized), because they were not supposed to be as loud as the Ultra Flows, Also they were cheaper than the Ultra Flows.
I had the Stock SLS Tips welded back on so by just looking at my exhaust you cannot tell that anything has been done.  If you crawl under my car the exhaust looks stock in its configuration except for the bigger diameter piping and the fact that dynomax is stamped on the mufflers.  I think it looks fine, because my exhaust guy did exceptional work.


2"/2" Y pipe, 2.25" DynoMax Super Turbo Mufflers

Anyway, my system consists of only the DynoMax Super Turbo mufflers in place of the stock units on my '99. I kept the stock tips and used stock sized pipe to connect with. I don't know the muffler part # but they had 2 1/4 in/out. As you may know, the '98+ STS mufflers are of a different design than all other Northstar mufflers. They are even made by Walker, so I didn't REALLY expect a great performance gain, just noise. For that reason I kept my stock mufflers in case I changed my mind later.

94 Eldo
2"/2" Y Pipe, 2" Flowmaster 40 Series Delta Flow Mufflers

I have a 94 Eldo with Dual 40 series Flowmaster Delta Flow Mufflers.  There was a mild low-end performance increase and a decent top-end increase.  The system in my opinion is almost too loud.. sounds very mean, SS, 5.0 T/A sounds... sounds like a muscle car but their is too much interior resonance with these current Mufflers.

Mark Went to Berea Ohio today to have the Corsa exhaust system put on  my 99 STS. Met Jim Browning (super nice guy) who gave me a tour of the plant and operation. Really nice operation.
This system is AWESOME!! You can actually see straight thru the muffler. Actually it is just straight pipes with a canister around it for their patented "reflective sound cancellation" technology. You can't hear the exhaust at all when your cruising down the road because of the sound cancellation technology, but when you put your foot in, it really comes to life and has a great sound. You can control how loud it is based on how hard you push it. I'm really pleased with the sound and the performance.

AH! The performance. Lets look at the numbers.
The trip was 210 miles. I started with a full tank of gas. I set
the cruise on 73mph. I got 25.4mpg @ 68.4 average mph.
I did 0-60 with G/Tech 6.37 sec (prior best time) 224 hp just prior to install.
After install 237 hp 6.13 0-60 Averaged 27.1mpg on return trip with same parameters (full tank of gas and 73mph).

Unbelievable performance and awesome sound. I'd say this is a winner.
Thanks Jim
Mark 99STS
Jason Hornig
Windsor, CA
Originally, I had the catalytic converter replaced with a FlowThru cat,
and the stock muffler replaced with a Flowmaster 40 series. MAN, was it
loud. As I drove off the shop's parking lot I thought I was being followed
by a monster truck. I was very satisfied, until I noticed that whenever I
started the car (on a cold start) and drove off, the exhaust would rattle
and burp the first run through the gears. After driving for a few minutes,
it wouldn't do it anymore. But that's not all. Whenever I had the car in
Park or Neutral and revved the engine up, it would sound fine as the RPM
went up, but as it went down, there would be a terrible sounding rasp coming from the exhaust. I went in to the muffler shop numerous times to have them try to figure out what was wrong, only for them to tell me that it is normal for all Caddies like mine to make that sound when a low-backpressure muffler was installed. I had the Flowie on the car for about 5-7000 miles until today.
  So today, I went in and had the Flowmaster taken off and had them install
a resonator and a Dynomax Super Turbo muffler with dual outlets (same style as the Camaros and Firebirds have). Then, to top it off, I had them weld on two Z28 vacuum style chrome tips, matching the chrome bumper perfectly. What I drove off with was a Caddy that had a very mellow but deep sound with very nice looking Z28 tips. The installation of the resonator completely cured my car's "strep throat." Now when I rev the engine I get a clean, rasp-free 50:50 engine to exhaust sound ratio which is a nice balance. To any DeVille owners suffering from this same exhaust strep throat that my car had, I highly recommend the combination of a resonator and a mellow sounding high performance muffler such as the Dynomax Super Turbo.
96 STS
Yesterday (wed) the car received it's exhaust modification.  After
researching the topic, I found I wanted to replace the stock mufflers and
expand the 'Y' pipe.  I went with the Dynomax Super Turbo mufflers but
upgraded them to the 2.5" size.  The Y-pipe was expanded to
accommodate, it was expanded out to the tips, but I like the stock tips and
left them alone.  After talking with exhaust modifiers, the 2.5 pipe was
large enough to handle flow on this engine up to 440HP (others may find
different but computer tests showed to stay with the 2.5").  Anyway, the
results are more than pleasing to me!  The first time I floored it was
about 55mph and I shifted into 1st at the same time.  The car went to
6800rpm's at the shift!!  Since then it has learned NOT to rev that high.  It
just revs through the RPM band SO FAST.  However, SPECIAL NOTE: 
The car didn't show hardly any gain with the stock air box on.  It makes
the difference ONLY when I remove everything and place the 10" K&N
cylinder on the intake tube.  Unplug the MAF (which has no screens) and
it squeals through 1st gear, on into 2nd gear and barks when it shifts to
3rd!  That is with an ABS wheel sensor unplugged.  It needs wider tires. 
Looking at the stock mufflers, the installer showed me how the core
goes down to 1.25" inside the muffler with many chambers.  The torque
steer is just phenomenal!  It sure is something else to drive!  When Luke
gets back online, he can give his account.  The noise level is great.  It's
not too loud, and cruising at 60 hardly noticeable.  But lay into it and it's
definitely there.  I must make it clear that without the K&N 10" cylinder, it
doesn't really do a whole lot!!  So if doing exhaust work, try very hard to
get the BEST intake flow possible, as each mod enhances the other,
literally being dependent for noticeable improvement.  That is this exhaust
mod account.  I hope it helps others when deciding to do the same!  
Email me with any questions!!
Larry Mocnik Bruce, I had installed from the cat back, 2.5" pipe, no resonator, to 2.5" y pipe, and Dynomax super turbo mufflers with stock tips. WOW!!!! What a difference!! Nice and quiet at idle, but give it some gas and the sound is really nice. Not too loud, but you know that you have changed the mufflers. I am very pleased with the change. I have not driven it enough to see any change in fuel milage, but it really woke up the performance. I also have a K&N filter with the air box gutted. I would highly recommend this change, it put me back $300.00.
White_Diamond I had the Dynomax Super Turbo mufflers installed on my 96 STS "The White_Diamond" two weeks ago.  Like everyone else said....WOW!! what a difference. They also increased the pipe size from 2" to 2.5" from "Y" back to the tips.  I had the stock tips welded back on.  I also have a 6" autophysics Big Mouth cone.  Unlike the K&N it is open in the front.  This and the exhaust made a huge difference, the car pulls really hard.  I didn't think it would make much difference so I hadn't taken the screen out of the Mass Air Flow Sensor.  Well I did this Saturday and it gave it a considerable amount of increased kick. Most people say that screen doesn't do much but they probably take it out first.  It was the last to go for me and I tell you it was a considerable increase in pull. The exhaust fully installed was $279 with tax.

OK...the pay off...speed is nice but I really did the exhaust for the sound and the gase mileage increase. My wife has a short commute to work and usually rides around a bit during the day meeting with clients.  She noticed that the mileage went from about 17city to 19city. I put it on the road this weekend for a 300+ round trip and we averaged about 24.5 mpg.  other trips before exhaust mods were 21 on the highway.

Please email Bruce YOUR custom exhaust configuration, including how it sounds and performs for inclusion here.