The Sweet Spot: Project Corn Star Gets An SLP LoudMouth Exhaust

Choosing the right exhaust for your car can be one of the most painstaking decisions of any build, and also one of the most rewarding. After all, what the car sounds like is pivotal to its enjoyment—and we think the enjoyment of others. However, the main problem with choosing an exhaust is what sounds good to one person sounds like utter crap to another. So how do you make your choice? Do you go for what sounds good to you, or what sounds good to the majority of your friends/fans/cohorts/haters?

We think the sweet spot is to be enviable. To illustrate that point, the other day we just happened to see a 5.0 Mustang cruising around. Naturally, we frowned in disgust; that was until we heard it. As it passed by, we had to begrudgingly admit that it sounded pretty descent—and that’s exactly what we were shooting for with Project Corn Star, our E85-fed, turbocharged 2002 Camaro SS. We wanted to strike admiration at the aural experience presented by the car—even if it was begrudgingly. It’s also the reason we turned to Street Legal Performance for one of its LoudMouth II exhausts.

The Great Debate

The debate inside the office about just what exhaust would go on Corn Star was fierce. Some wanted to keep it quiet, a sleeper of sorts. The turbo would already muffle the sound of our BluePrint 370 and a decent chambered exhaust could keep it quiet as stock. Not only would this allow the other fun turbo noises to be more audible, it would allow us to sneak up on the competition. There are few things cooler than a car that idles like stock but rips off 10-second passes and we could definitely see the argument on this side.

On the other hand, however, were the people who wanted it as loud as possible. These are the type of people that suggested just running the downpipe straight out of the front bumper cover right off the turbo and drive it around on the streets like that. While we can agree that that’s pretty cool, here in the great state of California it would be attracting a lot of unwanted attention.

On top of that, we’ve had cars that we thought were awesome because they were ungodly loud, but that stuff gets old fast—at least on a street car. While Corn Star will see its fair share of track duties, it is still destined to spend a good majority of its time on the street. And during that time, it would be nice to be able to carry on a phone call while cruising down the freeway. The adage of “if it’s too loud, you’re too old” applies here but we’ve been down that road before and we learned our lesson.

So that left us with a big decision. We didn’t want it completely silent. Though the thought of a sleeper is cool, a fourth-gen F-body with drag wheels and a giant intercooler peeking through the grille isn’t exactly subtle. And not exactly anywhere in the realm of sleeper these days. It would be like building a big-turbo Supra and trying to make it a “sleeper.” It’s just not gonna happen.

And since we prefer to keep our eardrums intact, that meant the car needed an exhaust—no bumper exits for us. That brought us to the decision of what exhaust exactly. At this point, it came down to chambered or straight-through designs.

While some chambered designs could give us the aggressive sound we were looking for, the LSX team worried that it would add excessive back pressure. Not that some of the systems out there aren’t free-flowing, but our turbocharged F-body is now particularly sensitive to back pressure after the addition of a Huron Speed turbo kit and a Precision PT7675 Gen II turbo.

In the spirit of reducing back pressure as much as possible, while providing the most aggressive exhaust note available (within reason), the LoudMouth II was obviously a natural fit and one of the first systems that popped into our head. After all, Street Legal Performance was actually responsible for building Corn Star in the first place (it’s an original SS car), so it’s fair to say they know a thing or two about making them sound good.

Street Legal

Going with the LoudMouth felt right. It checked all the right boxes. It was nostalgic, since SLP has a sterling reputation in the LS community after building some of the best fourth-gens to ever hit the blacktop, but at the same time, it made perfect sense. We’ve installed LoudMouth exhausts on cars before and there is definitely a science to picking the right one for your ride.

“With our exhaust, SLP’s mission has always been to deliver a unique audible experience that inspires individuality and self-expression through vehicle customization,” said Marcus Cervantes of Street Legal Performance. “SLP’s LoudMouth exhaust systems represent performance with an attitude. Through this mantra, we distinguish ourselves as passionate automotive enthusiasts who we are dedicated to innovation, performance, and quality. With our F-body kits, we have been able to accomplish this mission thanks to a great platform from GM. Each SLP LoudMouth kit that is installed on an F-body instantly improves the sound, performance, and excitement of the vehicle.”

We selected the LoudMouth II, as it comes with an actual bullet muffler—though it retains the straight through design we were after—unlike the LoudMouth I. The original LoudMouth is as aggressive as exhausts get, and though they sound awesome, they have a reputation for being a bit more boisterous than we were after. Thus our selection for the LMII was an easy one.

On top of that, if we found the exhaust note to be too much, or too little, the LoudMouth system is modular and is, in essence, three exhausts in one. If we found the sound too docile, we could swap the LM2’s bullet muffler for the LM1’s resonator, giving the car a much more aggressive note.

“SLP’s LoudMouth Exhaust is made to suit every individual,” said Marcus Cervantes of Street Legal Performance. “Each of our LoudMouth I and LoudMouth II kits are customizable with multiple muffler choices and will soon be customizable through a smartphone application.”

On the other hand, if we ended up feeling like the LM2 was too loud, we could augment it with the Pro Flo kit, which adds two additional bullet-style mufflers before each exhaust tip, further calming the exhaust note. On top of that, we could swap the standard muffler or resonator in tandem with the Pro Flo system giving us even more options and the best opportunity to get our exhaust system sounding just the way we want it.

In addition to being able to tune the LoudMouth just how we wanted it, the entire exhaust is constructed of 304 stainless steel, ensuring that it will look fantastic for years to come. SLP also recently updated the system with a set of double-walled exhaust tips that we felt would be the perfect jewelry to augment Corn Star’s already great looks.

SLP shipped us out our LM2 and we received it within a couple of days. With the exhaust in hand, we were ready to get to work.

The Install

While installing an entire exhaust system on a turbo car—that wasn’t one before—may seem daunting, we had already handled most of the hard work beforehand. The downpipe from the turbo runs down the driver’s side. Utilizing some 3-inch, mandrel-bent, 304 stainless steel piping, we fabricated an exhaust that hooks to our Huron Speed down pipe utilizing a 3-inch V-band clamp.

From there, two 45-degree bends and some straight pipe got our exhaust lined back up with the stock-ish exhaust system that was currently on the car. The previous system was being dropped to give the car some extra growl and make sure that back pressure was never a problem in our system.

Removing the old system was a breeze. We simply loosened the old band clamps and began twisting the tubes out of their old home. While this was pretty straightforward, you’ll want to take your time here as any exhaust that has been on the car for any length of time has not only been heat cycled quite a few times, it’s also likely got some corrosion holding things together a bit. Patience was key for us, but we had the old exhaust off the car in roughly 45 minutes.

The new system went back in like a breeze. First, a short pipe meets our intermediate pipe and routes back to the bullet-style SLP muffler. All of the new tubing uses slip-fit connections and comes with brand new band clamps and hardware. From the muffler, we slid the tube that routes up and over the axle, loosely bolting the hanger at the body in place. From here it was simply a matter of bolting on the exhaust tips.

You can see here that the driveshaft gets somewhat close to the exhaust, but we made sure that we still had plenty of room to spin it without interference. What's more, once the car is on the ground and the suspension is loaded, it's not even close.

This may be one of the hardest parts of the install, which isn’t saying much, as it takes a little finesse to get the exhaust tips lined up and even. Obviously, this isn’t hard but takes some time to make sure the tips are even and hanging with the same air gap from the bumper. Take note as we said air gap, you don’t want the tips up against the bumper cover or you’ll end up with a piece of avant-garde art.

The final part of the install was to cinch down all of the band clamps and make sure the exhaust wasn’t contacting the chassis or running gear anywhere. After dropping the car back on the ground, we double checked yet again to make sure none of our clearances had changed. We were all squared away and ready to fire her up.

The Sound

As Corn Star rumbled back to life, we immediately knew we had made the right decision with our exhaust. The LoudMouth II is a great combination with our turbo LS. It gave us the aggressive tone we were looking for without being too intrusive with everyday driving.

All of the fun turbo noises are present and accounted for but the LS still barks to let Mustangs know what’s coming their way. Drone with the system and turbo is non-existent. One of our first tests was to bring the car up to roughly 65 mph and tip in on the throttle in Sixth-gear to see what kind of drone we’d get, the answer being none. The exhaust is very aggressive but easily allowed us to have a cell phone conversation while driving it around town.

We even won over a few people in the process. Several of the people from “team quiet” were not only impressed with the car’s sounds but even went as far to as to say that we selected the perfect system for our vehicle. The exhaust is loud enough to let anyone that hears it idle know it’s got an aftermarket bump stick in it, but not loud enough to righteously piss off the neighbors if you have to leave for work early—though they still probably will be awoken.

All in all, we couldn’t be happier with how the car sounds and if we get a little too used to it in the future, we can also swap out the LM2 bullet for the LM1 resonator. As we said, the modularity of the system will allow us to fine-tune the sound in the future, but we think we hit the sweet spot.

Article Sources

About the author

Chase Christensen

Chase Christensen hails from Salt Lake City, and grew up around high-performance GM vehicles. He took possession of his very first F-body— an ’86 Trans Am— at the age of 13 and has been wrenching ever since.
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