The swing weight will change a bit if the the new grip is heavier, but it shouldn't affect the playability.

This will depend on the grip currently on the club. If the Midsize MCC+4 is your preferred grip, then you may see improvement in the feel/playability of the TSi1. You can change the grip back to the original if you do notice a change that is not a positive change for you.

That's a loaded question!
To be precise you need to know the weight of your current grip, and the weight of the new grip. If there is a dramatic difference then you should check the swing weight, and maybe swap the clubhead weight to compensate.

When I go for a fitting, the grip that I am using in the fitting is not what I get when the clubs come back. I always order an upgrade GP MCC Midsize +4. Never have noticed any differences in playability of my new clubs when they arrive. My fitters do not have my grips on their fitting shafts. Both are Titleist certified fitters and have a great selection of shafts.

Thanks for all the replies, guys! I wound up switching out the grip to the MCC Midsize Plus 4 Align to match thr rest of my set. The club feels a little "lighter" as far as head weight but I don't see any difference in performance. I may at some point try changing out the weight. Where might I obtain one?

I just buy them off eBay. Not worried about the quality of after-market weights, especially in a previous production model club. I do make sure they are sold by a site in the USA. I have been burned by orders from China taking my money and never getting them delivered.

Hi! Have you tried club manufacturers? If you're looking for original replacement weights from the club manufacturer, you can reach out to the manufacturer directly.

ref the weight, i asked around a few local pro shops to see if anyone had any, had no luck for the first few but on about the 6th shop i tried they had ordered some weights in for somone who never collected so they were glad to see them gone!! worth a try

Yep, totally agree!

I would suggest Golfworks. Link below to the specific weights under OEM Supplies

www.golfworks.com/.../

Oh, I even were searching for smth like that, thank you from me too!*