Got a 2014 SGS with 120R engine. Exhaust is V&H High Output Pro Pipe and it's dealer dyno-tuned with SEST. Exhaust noise doesn't bother me. Recently got a V&H "quiet baffle" to play with exhaust back pressure.

Question I have is does the engine need a new tune with "quiet baffle" installed?

Plan is to have local dyno shop do another tune anyway but wonder if the engine needs two tunes, one with and another without "quiet baffle"?

 

I would say that you're good to go as it is. The quiet baffle isn't going to have much of a negative impact on the exhaust flow out of the Pro-pipe.

 

When I switched from quiet baffle to standard it got significantly louder, although I've sort of got used to it now.

I found that at higher MAP values the VE was about 10% down with the Quiet.

 

My guess it'll just run a bit richer. A little stronger on the low end and not so much in the higher rpms.

 

Usually it will make it lean down low and rich up top. How much? Who knows.

 

Talked with dyno guy yesterday and he recommends two tunes. One for open and one with quiet baffle. Yes he gets paid for two tunes but price is not too high.

 

Sounds good to me.
FWIW, most folks like the low rpm manners (responsiveness) with the quiet baffle, not to mention the reduction in noise.
Performance/race baffles are designed for higher rpm (ie:4000-up) performance rather than the lower rpm (1000-3500) performance with the quiet baffle.
Bob

 

You will need to retune.

 

According to Steve at Fullsac, his 2-1/4" core makes less low end power and more top end power than the 1-3/4" That would indicate that the size of the outlet does change the airflow at different rpm. So, the questions are:
1. Is your quiet baffle more restrictive, or does it just use more exhaust packing/holes?
2. Are you running most of your cells closed loop? If so, the ECM will adjust fuel for more or less air flow up to about 10% (and gradually "learn" the new settings).
If you are open loop at 80 kPa and above (like most tunes), you will most likely be rich at full throttle, right when you need power the most. Probably not the best option.

 

I had mine tuned with the quiet baffle. Did not notice much difference when I removed it. I may try putting it back in to see if I can tell a difference now. With the quiet baffle in it has a raspy sound