Where you located?
I've ran that muffler with a 52.5 pilot and a 152.5 main without any issues in Ny, stock intake..

A low throttle "surge", where the engine hesitates is most often the needle, the Pilot has very little effect on how the bike runs when you start to open the throttle.  Pilot jets over 52.5 are seldom needed....although there have been times that cone filters and open pipes have made it really hard to get the bike to make run properly....even with a lot of jetting changes.

You need to choose a pilot jet that provides a smooth idle when the screw is opened up between 1.5 - 2.0 turns.  If you need to open the screw more than 2.5 turns to get a steady idle - then you need a bigger pilot jet.  If you can turn the screw all the way in and the engine hasn't started to stumble at idle.....the pilot is too big.

Once you have a pilot jet chosen......then the main jet should be selected that provides smooth running at full throttle.

Then you work on adjusting the needle to provide smooth acceleration at throttle settings just off idle...to about 1/2 throttle.  Take out the white spacer and use 3 washers that are #4 machine screw size.  If the stumble continues....take out a washer so that you just have 2.

Redryder652 wrote on 01/31/16 at 16:45:58:

They make good drinking straws...

No....there is a white spacer on "top" of the needle.  It pushes the needle down against a spring.  You remove the white spacer and install 3 steel washers that are sized for #4 machines screws......good hardware stores will have them (you most likely won't find them at Lowe's or similar Big Box hardware stores).  Start with 3 washers, and if you still have some surge take one washer out.

I got it, just replaced jets today back to 152.5 and 52.5 and did the famous spacer mod. It all makes sense now, I didn't know there was a little spring in there pushing up on the needle. Haven't ridden it yet, I'm waiting for New air fuel mix screws. 2 in case I screw one up.