i cant find the dyno post but didnt the isf make more power with headers and stock exhaust?

It probably makes more power compared to fully stock, but doubt it makes more than headers + higher flowing exhaust. More flow and less restriction with an aftermarket exhaust, so you should expect around 400 whp after upgrading both.

Hope this help buddy !

I installed headers with my stock exhaust for around a year.

Recently I installed my Joe-Z exhaust and the car is noticeably faster....search for my thread ISF Vs M3 and you'll see the difference.

Honestly, you should go exhaust first.

Got it with sikky's on it. Ill start looking for headed back systems

That was just with the Sikky headers (408 to the wheel)?? Or with an exhaust also?