Will I need a new impeller?

[Cody Townsend]

I have almost completed my home made intake for my rxp. I am using the factory elbow out of the SC into a coupling that than increases in size, and goes all the way up about 15" past the fuel tank. I don't know whether to use 3" or 4" hose llet me know what you think. Will this mod require a new or repitched impeller?

[Green Hulk]

Use 4" hose. You wont know if you need a repitch until you run the ski and take note of your RPM's

[Cody Townsend]

thanks for the tip. Maybe you could answer my ? How extensive should my engine be modded before I try the exhaust mod like on Cooke's ski? That looks sick. Will I notice any difference with the RR resonator bypass or just the annoying 2000-3000 rpm rumble? I'm ready to see some pics.

[Green Hulk]

Don't do the waterbox mod until you port the head, or add boost.

You won't notice a difference with the resonator bypass. Just a louder exhaust note and a very annoying sound at around 3000 RPM's.