According to a poll I did a while back, more than 1/2 of voters would or did spend their first modification dollars or exhaust. Easy decision on what to do, but the real decision lies in whose exhaust to buy. With more than a dozen companies making cat-back systems alone for Mustangs, the trying to figure out how it will work with your combination can be overwhelming. Don’t fret; we’re here to help.

We obtained 10 different after-cat exhaust configurations for 1987-1993 Mustangs (1979-1986 can use the same setups if converted to true dual exhaust). The goal is to illustrate key points of each system and explain how it worked on the test car to help you make an informed decision on what system might be best for you.

The test car is a mildly modified 1990 LX 5L (details here). The rest of the exhaust for the testing was comprised of MAC 1 5/8” EL headers into a Bassani 2.5” offroad X-pipe. Pictures of the systems follow each description and weights were included where possible. OK, now let’s get started...

STOCK

This may have kept the bean counters happy, but it left almost everyone else wanting more. The stock 2 1/4” pipe fit well, and it’s brushed stainless tailpipes while small, did add style to the side view. Mufflers were different sizes side to side to minimize drone at 2000rpm. Sound quality is livable until another stang with a worked exhaust pulls up next to you...

STOCK WITH DYNOMAX SUPER TURBO MUFFLERS

Next we welded a set of Dynomax 2 1/4” super turbo mufflers. Fit and looks stayed the same, but the sound really woke up. Drone at 2K was woken also. At 70mph cruise this setup was almost unbearable. Power felt up slightly too

2.5” FLOWPATH SYSTEM

This system is impressive at first glance hefting a 2.5” diameter throughout. The tailpipes are triple chromed and look nice. The muffler sections are HTS coated. This coating keeps the pipes in good condition. The system I tested had survived a Michigan winter, the muffler sections looked almost new. The chroming of the tailpipes though was another story entirely. Even with constant care by a VERY meticulous owner, the pipes rusted severely. In a milder climate this I’m sure, would not be the case. Other features of the system include flanged ball and socket type tailpipe to muffler section connections. I was pleased with the ease with which these went together. Fit of the system as a whole was excellent, Mac uses the term “TRUE FIT” for a reason. One slight problem was that with the muffler hanger installed the mufflers hit occasionally on the floorpan, after hearing from other Mac system owners on the same problem, I decided it best to remove this front hangar and the problem was solved. Another SERIOUS problem I had with the system was that the flanged connection to the tailpipe is welded and on the system I had, the connecting flange was clocked incorrectly. This caused the flange to crush the rear hard line to the left rear brakes, causing the test car to slide off of the road while braking from about 50mph. The test car and I both came out of it unscathed, bitter, but unscathed. Any competent muffler shop can cut this and rotate it to the proper orientation, but I realized the problem after the fact. Something to keep your eye out for when installing. The sound of the Mac system is distinct. The sound is deeper than a flowmaster system with the same sound quality. I think that if I heard another Mustang with an offroad H-pipe and flowmasters on it I’d lose my lunch. It was nice to hear how different this was. Power was good in mid to high end, but felt slightly down off idle. System weight = 42#. The pictures are of the system after one Michigan winter.

Flowmaster American Thunder (2 chamber) system

This system, for as much as people seem to get excited about it, really had my expectations up. The system is aluminized steel and corrodes rapidly. I would expect this system here in Michigan to last 3 years tops! If your car is just a racer, the good news is it flows very well. If you enjoy driving your car though, be wary. Drone was the worst of any system tested. Fit was good with only slight adjustment necessary to keep it away from the 245/45/17’s in the rear. This system with a stainless steel tailpipe upgrade is the way to go if you have to have flowmasters. Power felt nearly identical to the Mac system. Pictures are of system after 1 full year of Michigan weather.

Borla 87-93 LX 2” system

As soon as I opened the box the quality of this system almost smacked me in the face! The system is 100% stainless steel with polished tailpipes that you could shave in. One thing that concerned me at first was the small pipe size, but after speaking with the Borla engineers, I decided to stay open minded until it hit the strip. The system fit VERY well as I figured it would, given its’ smaller than stock size. Sound was a welcome change coming right after the Flowmaster system. The engine sounded more similar to a 4.6L Cobra than to the 302 with Flowmaster’s the car was earlier in the day! Power was up of idle and still felt powerful throughout the whole tachometer range. I was skeptical of what the times would be at the strip with this small system on. I was shocked. On the street this was a great system as it kept the car quiet, with no drone to speak of (Borla obviously did their homework). The tailpipes flare up slightly to a polished square intercooled tip. Only qualm I had with the system, as a whole was the lack of a manly tip. From the side it isn’t too bad, but from the rear it wasn’t the look I was going for. Judge for yourself. My second mishap happened with this system. During an overzealous testing session, I was torqing the car up in a parking lot. I run Lakewood strut and shocks and have great weight transfer. As a result of this, when the car came down on the suspension as I came off of the throttle, the mufflers kissed a speed bump. One was only scraped and the other is no longer with us! Scratch one beautiful exhaust system. System weight = believed to be 33#.

This system is aluminized steel with painted mufflers, which looks good, and the paint will help stave off corrosion. Fit was good, but the mufflers hung a tad too low. The tailpipes have a welded on polished stainless tip, so they’ll look good almost forever. The sound was very unique, and incredibly deep sounding. The sound was similar to a 351 with Flowmasters. The mufflers also have a very cool feature for the street/strip crowd. Each muffler has a cap held on by 3 wingbolts. Once the cap is removed the muffler flows straight through with no restriction. What this would add at the track was still to be seen though. A fellow stanger I know lives in northern Michigan and runs this system with a stock H-pipe. He keeps the caps off at all times until he comes down to the Detroit area. Sounds great like that. The second pic compares the size to a Flowmaster muffler.

>

Borla 2.25” 93 Cobra system

This is a great system! I found this to be probably the best all around system I tested. The piping is all 2.25” and the tailpipes flair out to 3.5” round slash cut polished behemoths. The Cobra system fits on all 87-93 LX 5Ls and 93 Cobras. Sound is identical to the Borla 2” system but kicked up a few decibels. More like the exhaust note of a supercharged 4.6L Cobra Very smooth and powerful. No drone, not obnoxious on the street and power felt up all through the car’s range. The track result showed that the car was as pleased with this setup as I was. I experienced a slight tire rub problem that it took a few minor readjustments of the pipes to fix. If you’re installing this system be aware of this. To me, this was the all out “WINNER!” if there really was just one of the whole test. Power felt the highest, it had the broadest feeling powercurve, and its track times were #2 overall. System weight = 34.5#

Borla 2.5” XR-1 94-95 Cobra system

The first two Borla systems used the same mufflers, and these were the only systems available for 87-93 Mustangs from Borla. 94 and newer Cobras all use XR-1 race mufflers, but this wasn’t an option for the old fox bodies. Borla found that the 94 & up system should fit on a fox. I was the first to try this out. The system’s fit was very tight in a few spots, namely the muffler to framerail clearance on both sides, but it comes with adjustable pipes from the H-pipe to the mufflers so there is some room to work. Any competent muffler shop can tweak this system around in about 20 minutes to make it work out just fine. This has the same 3.5” polished flair tips that the 2.25” system has. This wins my “Best Looking From the Rear” award. That’s all most people see anyway, right? This system also wins two other very prestigious exhaust awards. One being the highly envied “Fastest Times” for allowing the car to breathe enough to score the best 1/4 mile times. Second was the “Best Sound” award. This system is so mean that one of two things will happen, you will either drive around town in second to show off and get arrested, or sit in your driveway revving just to hear the sound of the exhaust and...well...get arrested. System weight = 37#. The first pic compares the tailpipe sections of the 3 Borla systems. The second pic is of the adjustable section of the system.

>

Bassani 2.5” Quiet Thunder System

This system is 2.5” stainless steel through out with 3” polished tailpipes. The quality of the welds on the mufflers were top notch. The system was almost a ringer for “Best Sound” awards, as it was tested with Bassani’s own X-pipe. Sound is deep, throaty, and powerful in a way that can almost not be defined. The tailpipes grow to 3” just barely behind the tire to maximize tire clearance and give the meanest looking view from the side of the whole bunch. The tailpipes come with a resonator insert that eliminates drone at 2K RPM. At about 200 miles into the road testing, the small fastener that holds one of them in vibrated out and became the world’s most annoying rattle. They were removed soon after. Without the resonators, sound quality is much better, picking up a few decibels, although drone is raised significantly and is very powerful at 1950-2000 RPM. Another thing to note is that fit of the mufflers to the framerail (mostly on the right side) is VERY tight, and the pipe over the axle liked to ride on the sway bar almost as much as it enjoyed riding ever so closely to the fuel tank heat shielding. This system is very high quality, but like the Borla 2.5” system expect to make a visit to the local custom exhaust shop to get the bugs out. Once tweaked, this will give you limitless years of a wicked sounding mustang! System weight = 42# with resonators, 40# without. This kit also comes with new hardware for the flange to the I-pipe and anti-seize, which I thought was nice.

>

Dr. Gas / Spin Tech

This is actually only a set of mufflers versus a complete cat-back system, so they were plumbed into a Flowmaster 2.5" system for testing. The Mufflers are designed using flow characteristics of exhaust to dampen the sound instead of fiberglass like many others. It is a straight through flowing muffler and I was excited as to what it offered by way of performance and sound. I've always liked the Dr. Gas X-pipes and this looked to be of the same school of thinking.

This is not meant to be all encompassing, but a guide to help you make the right choice for your mustang. Please keep in mind that all systems may sound quite different on your vehicle as your exhaust system and engine modifications are not the same as mine. Also, while the snowy, salty road daily driver should probably look toward one of the stainless systems, race only stangs and those of you lucky enough to live in more moderate climates need not consider this a requirement. All systems involved had a good showing and did better sound quality (if not horsepower also) significantly over the stock setup. Please contact the company you are interested in to speak with their technical staff to determine what is best for your combination and application.