1.) On a stock Evo, what is the typical horsepower gain (at wheels) for a down pipe, off road pie and cat back system?

2.) Can I buy a system such as the Helix one piece at a time and will it bolt to my stock system?

3.) Will a Helix down pipe and off road pipe bolt directly to my stock system replacing the cat and how much horsepower gain on a stock Evo?

4.) Would I get more horsepower from a Helix downpipe or Helix off road pipe?

Merry Christmas!

 

i'm not sure what the hp gain is but you can buy the system one piece at a time with no problems.

 

A full Turbo back set up, No cat lookin at 25hp. Maybe 5-7hp on a down pipe.

 

Go check out the exhaust thread. In the engine/turbo/drivetrain section. Lots of good info in there.

Not all systems will mate up to stock components and allow you to buy over time. Helix does allow this. A few other brands do as well.

Merry Christmas.

 

1) 17-25whp
2) Helix, yes, HKS yes, several others, yes. Just contact the manufacturer or seller for fitment. Or run a search here.
https://www.evolutionm.net/forums/sh...exhaust+thread
3) You would get more whp from replacing the cat, but risk throwing a CEL unless you get the 02 fix. My advice is get the dp for drivability...less chance of a CEL.