Question about two brothers shorty

[Danno$$]

Does anyone know if the two brothers shorty slip on is quiet compared to open headers (doesnt look like much muffler there to me) how about performance? do they need mapping? will they effect motor performance? thanks

 

[tegbusa]

They are Loud! I dunno about comparing it to open header thou.

 

[speed750]

Well, I ran open header the other day. It can't be that loud or you wouldn't make it 2 minutes on the street.