Hi all,

 

Will be taking my 71 to Marulan on the 21st.

 

It has a stock bluetop with pod filter and exhaust.

 

Exhaust wise i have 4-1 extractors, one resonator then one high flow muffler. I have a flange before the diff so i can get a quieter muffler/silencer on there without major hassles.

 

What are your experiences? Will a stainless muffler be quieter than a mild steel? What would be least restrictive on performance? Extra high flow muffler in middle or quieter rear muffler with silencer?

 

these are the rules of Marulan:

 

Test 1: Maintain 5000 rpm for five seconds. Requires a reading of less than 92db when measured 5m directly in line with the exhaust tail pipe.

Test 2: From the same position, return the engine to idle rpm then flatten the accelerator to 5000 rpm for a reading of less than 95db.

by the sounds of it you have a similar exhaust set up to my ke70. 4 to 1 extractors a hotdog style resinator then a straight through sports muffler. at tafe we did a stationary noise emission test on our cars. i can tell you that at 3000rpm 1.5 mtres away at a 45 degree angle from the outlet of the ehaust. mine was 91 dba, i do only have a 4k-c though. if you have a flange at the back i'd make up a section with a proper baffle if your that worried. what will happen if your car is too loud?

A dump tip on the end of the exhaust will always help the reading get that little bit lower

Get a rear muffler from a wrecker, the bigger the better, and make it so you can bolt it on in a couple of minutes.

 

I'd go tri-chamber rather than straight-through. One with nothing in the middle chamber at all, and each end is packed with glass to absorb noise, which is the sort I use on the Altezza and the KE70.

 

I have run a few on the Altezza, cutting them open to see how the insides matched the noise, and basically the heavier the walls are the quieter is gets inside the car, and anything that is not straight-through is a lot quieter.

 

Try this-

 

http://autospeed.com/cms/title_Giant-Muffler-Comparison-Detailed-Test-Results/A_0383/article.html

You know 95db is twice as loud as 92 yeah?

 

If its just a stock engine throw on the biggest proper muffler you can fit.