3" Custom Exhaust Part 1
The new exhaust is on! First impressions after one week of driving is it really woke up my engine. Low-end torque is much stronger and it builds boost quicker! See below for my detailed review of performance and sound. First the sound clip and photos:
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The exhaust goes from my Doug Thorley headers with 1.5" primaries to a 2.25" Tri-Y collector on each side to a 2.5" downpipe. From there, it enters the 2.5" Magnaflow high-flow catalytic converter (
Part # 445006, $240:
Then it bumps up to a beefy 3" from the cat back. The stock pipe is 2.25" exiting the exhaust.
Going to 2.25" to 3" piping is an 80% increase in surface area size and a roughly 83% increase in cfm's.
Next it goes through a 3" Borla ProXS muffler (
Part # 40359, only
$84 on Amazon):
Finally, it goes over the axle and exits out a 3.5" exhaust tip. This particular one is 12" long since I don't like the look of the tiny short ones.
I'm ecstatic on how it turned out! A local shop in Sacramento, Muffler Tech did the exhaust work and did a great job. Competitive pricing too for what I wanted done as I got a couple of quotes. Total was $636 for the exhaust installation plus $84 for the muffler and $215 for the converter (sale) came to a total of $935.
UPDATE: Here's the dyno graph! I had some heat soak after the re-tune so it might even be more than this on the first or second run!
Max power gain is +16HP and +22TQ! Peak torque gain is 15TQ! Due to where it was added on the power band, peak HP is unchanged. Can really feel the difference in power from 2000 to 4500 RPMs!
You can see the result of the heat soak as I made about 0.5 PSI less boost and power starts to nose dive quicker above 5000 RPMs.
Power: The power band on the engine is much bigger now! The throttle pedal is very responsive and it builds boost with less throttle and at lower RPM's. The mid-range is where it's the most noticeable, I've only pushed it to WOT once in the past week because I'm going too fast way before then! I logged some WOT runes but my tune was between
13.2 - 12.5 AFR's and totally off now, it flows that much more air! Previously was 12.0-12.2. Even with the AFR's off, it STILL had a
peak gain of +17RWTQ and +10RWHP at 3500 RPM (where you want the power)!. I am in the process of re-tuning it and will post up a graph when it's done.
Sound: It's kinda loud, louder than I wanted. It'll quiet down the more I drive it as the muffler insulation settles down. The tone is nice at startup and idle, it's a low grumble that's quite intimidating. Cruising around town it's on the loud side under acceleration but sounds great when held steady. At freeway speeds it has a loud drone at 2100 RPM's that I hope quiets down over time as it's hard to hold a conversation. At WOT, this thing is nasty! Growls and screams but nothing raspy or ricey. If the freeway speed sound doesn't calm down I'll see about putting in a resonator to help with those frequencies.
Results:
HP Increase:
0 Peak, 16 Max gain*
Running Total:
+131 HP
*This is one of those things that's hard to show on a dyno graph when just comparing peak power output. There's no peak gain because the Peak HP is over 5000 RPM's while the exhaust power band is from 2000 to 4500 RPM. Cars built for very high RPM HP numbers that build all the power on the high-end might look great on a dyno but in real world driving aren't as much fun to drive as one that builds power in the low RPM range. That's why I don't chase power up high.