Smoke comin from tail pipe

hey guys and gals i’m worried about my 98 gs-r i’ve been noticing smoke coming from my tail pipe and just wondering if it is just blow by and if it is just blow by how is blow by caused?? Usually it blows out grey and sometimes black and lil blue but it’s weird it only blows out when i’m shifting around 7500 in vtec and sometimes when i’m goin down hill not using gas and i come to a stop light idling what could be causing this to happen ??? i’ve got a 98 gs-r chipped computer fuel pressure regulator set at 39-40lbs stock header cold air intake 21/4 exhuast hollow cat dyno tuned at 147hp and 115tq
please help me

Blow by is caused by wear - aka shifting at 7500 rpm.

You abuse the engine, it’ll smoke eventually. Sounds like the rings are probably getting worn a bit, possible valve stem seals as well since it smokes during decelleration as well.

A little black smoke when you’re shifting at high RPMs is normal - greyish-blue smoke is oil being burned.

i agree sounds like your rings are going out. you should have a leak down test done to your engine. at least that will give you a better idea of what really happening inside there. how often are you shifting at that kind of rpm?