So, I have an MHI turbo,
resonated test pipe (probably Megan),
and a 3" SS straight-through Magnaflow (4" tip) on a 3" CBE that I can't remember the name of. Anyway...

I'm adding a 4" 45* or 90* elbow (whichever fits) that will extend up
approx 10-12" and to the left.
Has anyone passed MRLS's sound limit with a similar setup? it's a long drive and VERY pricey so would hate to get kicked off.

My plan b is to put the stock CBE and do a retune... but I can't imagine an FP Green being too happy with that kinda back pressure.

Opinions?

This is approx where the elbow will set. I am worried a bit about heat; I've seen a melted car once.

 

When we had issues passing for sprint car races we put 45deg tips and pointed them down to the ground.

Seems like pointing up would make it worse.

Another trick is find the location of the sound Meter and point your exhaust the other way.

 

The MRLS sound tower is on the straight before the kink, on the right side I think. I would point the deal to the driver side, maybe 5-10* below level. 90db is funny. A lot fo stock cars won't even pass that...

 

Isn't your plain jane air Impact gun 90db?

 

Below horizontal? All the tips I've seen are at approx 45° upward. Hm.
I had a WRX that passed With a test pipe and a reasonable muffler. That car was uncommonly quiet though.
Maybe I should just retune with the stock car back.

 

Most air tools are over 100.

 

Some cell phones ring at 85+

Air tools can be over 100 but they're immediately next to you. Typically tracks measure 20-50' away.

 

Yes.Pointed to driver side will point the sound away from the sound tower. Pointing it slightly down will angle it towards the ground a bit, which will make it a bit quieter.

 

I like that idea; I've seen more than one car with melted bumper covers from the exhaust pointed upward. Running a lil' rich, I guess.


I'm tossing on my stock cat back and retuning with less boost. Gonna see how it does. I may go that route as long as I'm at at least 300-350whp.

 

You'll melt your stock cat with any decent power and speed, ask me how I know lol. Best bet is as suggested, get the tip to point away and you should be fine. You can also lift by where the tower is, lots of small tricks depending on the conditions.

 

Also add a resonator or mini muffler to your current exhaust. Put it where the stock resonator is, right before the rear diff. Not in the test pipe.

 

if the sound guy is on his toes he can bust you for that. they'll usually warn against that in the drivers meeting

 

I wouldn't be using the cat, only the cat back portion of the exhaust.

Possibility, if I have the time. In my town, it's pretty much impossible to find a muffler shop willing to work on non-carb-compliant cars.
I know the simple option seems to be to take the exhaust and muffler down and just have them measure and replace, but it would be my luck it would not fit when I got home. I have really bad luck when I trust Poole that way. Lol
I preferr to have it installed on the car.

 

I tried a Greddy Evo2 w/ a Coastfab 10" mini muffler added back in 2011, and still hit 94 when WOT. It depends on the weather that day, as there was a whole lot of cloud cover in the morning, so lots of people were blowing sound, but the afternoon went fine once it was sunny. If you do an elbow and point to the left like you show, you should be okay. Most of the setups I've seen at Laguna point up, not down for whatever reason.

 

All I have is the exhaust listed above. I don't foresee myself being able to get another muffler installed, but we'll see.

I assume tips are up to keep noise from reverberating off the ground, but I could be wrong.