Front mount

[gtirchris]

Have a friend who wants a front mount for his R but he wants to know which one to choose between these 2 sizes
1.) Core Length : 24" (600mm)
Core Height: 12" (300mm)
Core Thickness: 3" (75mm)
Inlet Size: 2.5" o/d (60mm)
Outlet Size: 2.5" o/d (60mm)
"End to End" Length: 31" (775mm

2.)Core Length : 21" (525mm)
Core Height: 9" (225mm)
Core Thickness: 3" (75mm)
Inlet Size: 2.5" o/d (62mm)
Outlet Size: 2.5" o/d (62mm)
"End to End" Length: 31" (775mm)
which would be the best out of the 2 to get

 

[kirko]

bigger is better if you can shoehorn it in