Is it worth the upgrade from Buschur Ported 65mm to S90 (70mm). Would the 74mm version need any modification to the Intake manifold?

 

Hard to say a larger TB is worthwhile without understanding other things about your power goals. I remembered reading a post from JohnBradley concerning the TB and intake manifold restrictions, which may help you decide:

https://www.evolutionm.net/forums/ev...ody-3-tbe.html

 

Only if you're going for over 800whp, and you already have an upgraded intake manifold (Magnus V5 or similar).