I have the 6to1 ceramic header and 2.5" performance exhaust from MSA on my 240 and 280.  I really like the sound and the ceramic header does a fantastic job lowering the under hood temp. 240 sounds great with no resonator at all speeds.  280 had to have a 20" resonator installed at local exhaust shop, generic one they had on hand.  Charged about $50 IIRC.  It had a horrible drone sound on the interstate and was god awful loud pulling hills around town.  I can only guess the bigger 2.8 was the cause of the drone sound, everything else was the exact same as the 2.4. I was thinkinging MSA had reducing adapters for smaller diameter exhaust? 

 

 

 I have to agree with you on this. My L26 had MSA 6-2-1 header + 2.5” straight back to a turbo muffler. 

Sounded awesome. There was a drone at 2-2.5k rpm but bearable.

 

Then upgraded to an L28 and the drone with the same system was unbearable on a long run or while cruising about. The ZStory exhaust with a rather long resonator all but eliminated it to about 80-90% less drone.

 

In addition to displacement, i do think that the cam overlap and lift has a lot to contribute to this annoyance. Also advancing a cam will make it louder.

 

But I won’t run my L28 again without a resonator.

 

Did your L28 have a hotter than stock cam?

 

 

 

No it's stock L28 except for port matching which was a significant increase in air/fuel flow. I added a potentiometer for more fuel to compensate for more air flow. It ran lean and bucked like crazy until 2,500 rpm. Now it pulls like a tractor.

That’s a great outcome! Very pleased for you. [emoji106][emoji106]

 

My L26 had a beautifully ported E88 head and went so well. These cars seem to love a good bit of porting / matching.

 

I did the MSA 6 to 1 Ceramic and 2.5 all the way back. Did both resonator and muffler. See;