Scooterotica

Been running my 03 PX200 with a Harry Barlow stage 4 tune,standard carb with a sip road 2 pipe for a year with a drilled filter and a 128 main jet giving a nice brown colour when plug chopped at over 3/4 throttle.
Just fitted a steel Revolver pipe and plug chopped again the same,plug colour was slate grey.Went up to a 132 main and even a 135 and still getting a greyish plug colour? All other jets are standard P2.
Any ideas how to get a richer plug with this pipe please?

Had the same problem on a Malossi 172 with standard carb. Now running 132 main and so far hasn't gone bang.