Do u think that the Stainless Steel guide rod 20 lbs is better than the one that original on that come with the Smith Wesson sd9ve

Better for long term durability when shooting +P loads perhaps, but there's really nothing wrong with the factory captured RSA.

Just as good for 3 times the price.........
Be careful about spring weights. The recoil spring must be matched to the ammo, and a too-strong spring causes ejection problems. If the empties land 3 to 6 feet away, you're just right.

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Science plus Art

I assume that landing on my head/cap is appropriate.

It doesn't bother me but I have a hard time understanding why my SD9VE doesn't eject more to the right.

Others have posted that their guns sometimes eject into their shirt pockets. Now that's class!

Funny mine had a couple hit my baseball cap... I was told that upgrading the spring to a 20 lbs would be Good less recoil and less wear on the bottom half of gun?

Oft-repeated myth. The recoil spring must be matched to the gun/ammo for proper function. It also helps to hold the gun correctly.
Ejecting in the wrong direction usually means adjust the ejector, or in some cases too strong a spring for the ammo/ shooter. If you let the gun flip and flop around when you shoot it, good luck on where the empties go.

I put a 15# recoil spring in one of my M&P 9s that I often let beginners shoot. For the "wimp grip" shooters, the casing would come back more toward the shooter with the original spring. +P ammo would also have solved it, but that's not what I give beginners to shoot.

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Science plus Art

Awesome video on cost effective mods. Even covers guide rod selection.