Will I need a remap going to 99 catless header from

Hey guys I gutted my stock cat a while back on my bike and got my power commander all dialed in and it's running great. Well I scored a 99 catless header for cheap which I hear is better because of the larger head pipes. Do you think this will mess up my tune that I am running for the stock header and gutted cat? I'm hoping it won't need much if any tuning changes done because it took forever to get it running perfect. What do ya all think?

You won't NEED a new tune, but your current tune could probably benefit from some adjustments.

I was kind of wondering that. It currently is running a little rich so maybe it will even out after the header swap. If not I will have to do a bit of fine tuning. Thanks for your reply..

Grind the primary pipe welds down on the ‘99 catless headers before installing. It will increase the cross sectional area of the primary header by ~30% at the crucial exhaust port exit location. A little bit of work will pay decent dividends on the top end and over run.

Rush, thanks for the tip on grinding the welds on the 98-99 catless headers' primaries. Is it easy to see the parts of the welds to grind down? How far into the header should/can you grind?

sfdownhill, 4/24/2018 at 11:22 PM

Rush, thanks for the tip on grinding the welds on the 98-99 catless headers' primaries. Is it easy to see the parts of the welds to grind down? How far into the header should/can you grind?

It’s a piece of cake with a Dremel and patience.  The welds are located just inside the primary header pipes where the flange mounts them to the engine. You can see the circular weld bead when you look in the end of the pipe. I took them down to almost flush. Others have ground them down and polish the connection so you can hardly see that there was a weld there. If I had known it wouldn’t compromise the integrity I would’ve done the same thing.  Don’t go to deep.

There was a thread with pictures... i don’t know if it still exists. A search might show you everything you need.