You have to remove the console and splice into some wires, I think you mean SOLDER and Yes, you should solder the wires so they don't come loose. It comes with full set of instructions that are are very easy to follow.

 

Get an ultimate racing test pipe, no splicing of wires of any kind and no cel as it has a built in mechanical fix.

 

The HKS downpipe because of its 68-70mm design is fairly good for the stock turbo EVO. You'll see about 5-10whp depending on if you run a test pipe or not. That said you may want to consider a larger 76mm downpipe if you plan on being aggressive with mods down the load. There are substantial gains going to a 76mm downpipe for the Stage 2+ car. Helix, Tanabe, etc. all make 76mm downpipes which will clear the ACD. If you're planning to stay at Stage 1 (no cams, etc.) then stick with the HKS, that's a good choice.

Cheers,

Gary
Gruppe-S