Koma

iTrader: (3)

Engine side of the headers are bolt-on though correct? That was my real statement really. I wouldn't really plan to use the stock exhaust if I was to get aftermarket headers.

TexasLex

Yes, the engine/cylinder head side of the headers bolted directly on without any fitment issues.

JBrady

Yes, read through my post on the previous page for specifics.

gsshopper

OK, with apologies for what will be a long post, here's my experience so far with my own installation of the S&S headers and a cat-back exhaust system.



I dropped off my car at a local muffler shop on Monday, and picked it up late yesterday, after a 2-day install. Most of the first day went toward installation of the headers and reinstallation of the stock cats. Day 2 focused on fabrication and installation of a cat-back exhaust system.



The only issues encountered during installation of the headers were (1) one of the O2 sensors seized and the threads stripped during removal, so had to be replaced; (2) the steering column shaft had to be removed / reinstalled in order to install the driver's side header.

Here are the parts used in the cat-back exhaust system, from front to back:

• 2.25" custom piping from the cats to a center muffler
• Magnaflow 18" 12258 center muffler (2 x 2.25" iin / 1 x 2.5" out) - this also served as the front merge
• 2.5" custom center pipe to Y diverge
• 1 x 2.5" in / 2 x 2.25" out custom Y diverge (fabricated onsite)
• 2.25" custom piping from Y diverge to rear mufflers
• 2 Magnaflow 18" 11265 rear mufflers (2.25" in / out)

And here are a few pics of the installed system (on my dirty car) - I didn't have my camera with me when the car was up on the rack, so I took these pics at home.

First, a side view of the rear mufflers - the shop did a good job of tucking them up as far as possible (the Magnaflow ovals are a bit taller than the stock mufflers, so they do hang down a bit), and aligning the (stock) tips correctly at the rear skirt:



Next, a side view of the center muffler / resonator. Again, the Magnaflow muffler is taller than the stock part, and the front pipes protrude due to the slightly lower position of the cats after installation of the headers, so I lost about an inch of ground clearance:



Here’s a side view of the front Y merge connecting the cats to the center 2-1 / 1-out muffler:



And here’s a view from the rear of the Y split that connects the center muffler to the rear mufflers:



Finally, here’s a view of my car in cleaner times. It’s actually a bit lower than pictured here, after installing a set of Tein coil-overs:



Now for the results. Note that the following is a subjective evaluation – I did not do before / after dyno tests.

Some background: a couple of years ago, I replaced the stock torque convertor with a Dragon TC and the stock rear end with a Supra TT LSD. And I have 255/40 tires on the rear wheels. I got good (much better than stock) off-the-line performance with this combination – mashing the throttle from a dead stop produced a satisfying, bog-free launch, with no wheelspin (BTW, I live at over 5000 ft elevation).

That’s changed with the new exhaust setup. I tried 4 standing starts during a test drive today, and in all four cases, I got rear wheelspin – nothing dramatic, but a definite change for the better. Even more noticeable, however, is the increased midrange power. Flooring the gas pedal from a constant 35 or 40 MPH produces truly enthusiastic acceleration.

But I have to qualify my endorsement due to the dramatic change in sound between the stock and replacement exhaust systems. One’s impression of performance is influenced so much by the sound a car makes when under acceleration that it’s very hard to gauge how much better performance is when the source of improvement produces such a profound change in sound. And there’s no question that my new exhaust sounds more powerful.

There’s the rub. One of the things I really appreciated about my stock exhaust setup was the ability to bolt away from a stoplight without attracting law enforcement. But my new exhaust system sounds more like an American muscle car than a Lexus. The sound is noticeable even with modest acceleration, so the character of the car is changed significantly.

So I am planning a return trip to the muffler shop to add a couple of resonators, probably a pair of side-in / side-out parts in the stock locations in front of the rear mufflers. I’m hoping that this will make my car sound more civilized, because my next planned mod – an SRT HFI intake / ECU, will also make the car noisier.

BTW, if you’re considering which mod will give you the most bang for the buck and your priority is off-the-line acceleration, I recommend that you upgrade your TC first, and then your exhaust system. On the other hand, if you’re looking for a combination of improved performance and more aggressive exhaust note, the headers / cat-back mod is hard to beat. In any case, there’s no question that the combination of TC and headers / exhaust upgrade makes the SC4 much faster than stock.

JBrady

Excellent post. Very interesting how the car with TC and LSD would not spin off the line due to the loss in power that all vehicles that are not turbo/supercharged experience at altitude.

That it will spin now and the "butt-o-meter" indicating a pronounced mid range improvement we can see that this upgrade is making power.

Sound level is another thing. In our discussions prior to this install I suggested for my LS that I would be running twin 2.25" resonators after the center resonator and twin 2.00" final mufflers as the smaller size will be quieter.

Sound level and quality is certainly subjective. Producing a performance exhaust with the same low dB of the stock system is not easy. Nice effort and I am certain everyone is looking forward to your continued reports

GILLEXUS

iTrader: (14)

The 18" center muffler you installed is that the same as a resonator pipe??
What muffler shop did your header install.
It is odd that the shop had remove your steering colum shaft on the drivers side, SRQ400 has the same car and did not have that problem

gsshopper

Gillexus, I don't really know if there's a useful distinction between "muffler" and "resonator", in terms of function, but I believe the latter term usually refers to parts that are installed in-line, rather than just in front of the tailpipe(s). The center pipe part on my car is essentially a large oval muffler with two pipes in and one pipe out - since it's in-line, let's call it a resonator

Installation was done by House of Mufflers on East Evans. I also got an estimate at Bud's, but Cory at House of Mufflers was willing to work with me to get the sound the way I wanted, so I went with his quote.

GILLEXUS

iTrader: (14)

gasshopper, what did they charge you for the header install? do you know if their labor was about what guys have mention 4.5 - 6 hours.?

gsshopper

Here's an update to my original post last month.

After the initial installation of headers and cat-back exhaust produced an exhaust note that was too "American muscle car" for my taste, I had the muffler shop add two more mufflers. Originally, the plan was to install 2 side-in / side-out units, but they turned out to be too large (18"), so we decided instead to add two Magnaflow 11375 units (11") in the locations where the stock resonators were, just forward of the rear mufflers (since they are not a side-in design, they sit diagonally, as you can see in the photos below).

Bad weather and a business trip prevented an evaluation of the result until this week, butI can finally say that the combination of sound and performance are just right - a bit louder than stock, but certainly not obnoxiously so (one of these days, I might screw up the ambition to post a sound clip). And there is a definite increase in power across the board, making the car much more enjoyable to drive.

BTW, there's an interesting psychological angle to the noise issue. I mentioned in my November post in this thread that it was difficult to assess the performance difference after the initial install, because the exhaust note was so different from stock. I found myself compensating for the added noise by going easier on the gas pedal - good for gas mileage, but not conducive to a sense of enhanced performance. Now that the exhause note is more civilized, my right foot is less inhibited, and it's much easier to appreciate the performance improvement.

Aside from the cost (over $2K in parts and labor, including headers), the only downside to this mod is that the new exhaust system reduces clearance significantly. I had previously installed adjustable Tein coil-overs with a 1" drop, but to prevent damage to the new exhaust system, I will probably end up taking back at least half of that.

Here are some photos of the result. First, a view of the entire system from the rear of the car:



And here's a view from below. Note how the 2 intermediate mufflers sit diagonally in the stock locations:



Finally, here's a view of the front end of the 2-in / 1 out center resonator, showing the connections to the catalytic convertors:

TexasLex

Looks nice. At any point did you have a problem with interior resonance/drone, or was it initially just too plain loud for your tastes?

gsshopper

No resonance per se, but there was a distinct, low-pitched rumble with modest application of the gas pedal. This is absent with the modified setup, but there is still a satisfying wail at WOT.

BTW, I just returned from a 1200 mile roundtrip, where I got to really push the boundaries of the new exhaust system. I must say that the power increase is far greater than I thought at first. Passing is effortless, even at partial throttle. I tested acceleration from a standing stop several times, going up interstate on-ramps, and the car can easily hit 90 by the time the (short) merge lane runs out. Very addictive!

JBrady

Great observation. Here is a very good example of the difference between a more RESPONSIVE system and one that only increases the PEAK output. Engines in street driven cars need to be flexible and responsive. Giving that up for a peak gain is RARELY satisfying. Virtually ANY performance minded individual can drive 2 cars back to back with identical PEAK outputs but one is very responsive and flexible. MOST would gladly pay an additional 2 grand on their new car to have the one with the more responsive engine (all other things equal). This is WHY people spend money to modify their cars and is WHY I stated in the header condensed thread in the GS section that dyno numbers are only a PART of the gains to be had.

gsshopper

John, not enough people credit your hard work and persistence in making these headers available, perhaps because there aren't too many of us who have installed them yet. Even though this is not an inexpensive mod, as I've noted before, I want everyone to know that it does, indeed, deliver a significant performance improvement, and in my case, I consider it money well spent. I just wish I lived nearer to a highway where I could use this power more often!

Thanks very much for your efforts, and to all the naysayers I say - you don't know what you're missing!

JBrady

Thanks and you are welcome

If you like how your car runs now... at altitude... try driving down to sea level

TexasLex

Damn, car ended up being in the first shop for 6 weeks, then I went back 2 or 3 times because of an exhaust leak that they couldn't fix and blamed it on the intake resonator. So I took it to another shop that kept it for 3 weeks and they told me the header flange on the exhaust side was warped. How did they manage to warp a 3/8" steel flange while welding it, it's not like they were rushed for time. I am beyond pissed.