Gernby

Wouldn't it be beneficial to be "almost" legal in California? Aren' the cops in CA more likely to ticket you if your exhaust smells illegal?

Vitt

No question about it. I personally wouldn't even think of using a TP. It's not like they do a visual check under your car if there's no reason for it. If they smell it I'm sure they'd question it and also want to look under your hood for starters.

j.mart

I'm still very interested - can't wait to see how things work out with your midpipe and the Q300. Did you manage to sort things out with the exhaust?

nb12

Would this fit a 3 inch single as well?

Gernby

My mid-pipe would work great with a 3" single. I actually designed my whole system as a 3" exhaust, and tested ~8 different 3" mufflers in various configurations. It wasn't until late last year that I decided to test a smaller diameter pipe from the header to the expansion chamber, which is when I discovered even better midrange. The process to install a 60mm, 63mm, or 76mm muffler secton to the back of the mid-pipe would be the same.

Gernby

I did get the Q300 installed with my mid-pipe, and the results were as expected. I'll post the plots of the results soon. Unfortunately, the Q300 is still way too raspy. I will have to put sound deadening material inside the expansion chamber later this week, and see if that reduces the rasp enough.

Gernby

After doing all my data collecting with the Q300 and test pipe and also with my mid-pipe, I decided to mount up a conventional HFC (Berk style) with the Q300 to see how it did. I liked the tone of the Q300 better with the HFC, but damn does that thing drone!! At light throttle, the drone is really bad.

In order to test the drone, I use a 4 channel surround sound digital recorder, as shown below. Then I use custom software to isolate the component of the recording that is generated by the exhaust. I do several of the rtecordings at full throttle (WOT) and also at a "cruising throttle". To get a repeatable cruising throttle, I use a special FlashPro map with a target throttle plate that is restricted to maintain a nearly perfect 500 mBar. At that load level, I can accellerate very slowly in lower gears, but it will just barely maintain a speed in 6th gear.

Below are graphs showing the output from the standard Q300 with a test pipe, standard Q300 with an HFC, and the Q300 with my mid-pipe (integrated HFC). The Y axis is linear sound level, but is not any particular unit (not dBA). A higher number indicates more noise...


Full throttle

Cruise Throttle

billios996

the sound graphs are impressive

j.mart

Certainly impressive drone attenuation - it would be very interesting to add a fourth data set to your graph: Q300 w/ the stock cat. Would that be possible?

whiteflash

I take it you don't have a piece that simply replaces the OEM cat? Your piece must go all the way back to the axle?