Heavier / Stiffer Alternative to S300

[DuffDaddyKev]

I got fit into my MP-25s back in 2016 and they have True Temper S300s 105g in all of them. Since then, I’ve gotten stronger and feel like my swing speed made a big jump. I recently was fit into X Stiff (frequency 6.5) in my driver and woods, and figure I should give it a try for my irons as well. Lately I’ve been struggling to feel where the iron head is at. 
 

Any recommendations on shafts to look into? 

Edited May 15, 2020 by DuffDaddyKev
Forgot to add weight of shafts

[RickyBobby_PR]

X100, modus 130x, px6.5, to name a few. Get fit to find the best March for your swing. It’s possible just going to s400 would work. 
 

There’s not flex standard for shafts so the x stiff you were fit for could be a stiff flex in another brand.

[03trdblack]

Just the standard Dynamic Gold s300 would be heavier and stiffer than the 105g version.