I put the 10" one on my Met Pro. Made an incredible difference, especially when coupled with the external subwoofer! Definitely fills out the sound quality on the backbox speakers, for sure. For what it's worth I ordered direct from Flipper Fidelity and skipped the "volume control" and I think I may have to go back and get that, just to bring up the relative volume of the backbox speakers compared to the cabinet speaker.

I got a 10inch on my GBPRe and it really rocks,as opposed to the 8 incher on my B66LE!

The volume control is really important to getting the sound right. Don’t skimp on that! You can add the L-Pad later if you want; it’s not too difficult, but IMO nicer to just buy the FF one. They are expensive but really worth it, especially for games like this where the music is critical

Either the 8” or the 10” speaker will be great; if you are concerned I would spring for the 10, but the volume control is more important if you are trying to save a couple bucks.

Another option, FF back box speakers and a powered sub hooked up to the cabinet speaker

Having a powered sub is a better way to control the sound - the bass will be tighter and louder, less “boomy” but the trade off is you have to power it separately and deal with The sub enclosure being outside the game, which not everybody likes.

I've heard the 10" on a Met pro. Sounded noticeably deeper. I have the 8" on my Tron. It's definitely loud, rattles the glass, but not quite like the 10".

10", scientifically proven better by Dr. S. Tyler

I've had all the set ups discussed. In my experience to get the best sound I would buy the Pinnovator's external sub mod ($30), and connect a 10" external sub that u can buy for less than $100 on amazon. I bought several boards, and then just switch the external sub to the appropriate game.

Highly recommend FF in any pin especially a music pin. Have them in my KISS with the 8" woofer and they made a Big difference. Stern's stock speakers are junk.

Keep in mind that the resistance (Ohms) might the different. Somebody over at the Metallica thread fitted Clarion car speakers inside Met. Not sure if he needed any additional hardware.

https://pinside.com/pinball/forum/topic/metallica-owners-thread

I have a Met Pro with FF with 10” and it sounds great. I don’t have any experience with external subs on pinball machines but do have with home theater setups. Cheap subs like the ones mentioned all over Pinside generally don’t sound very good. Obviously they increase the overal quality with stock speakers but in my opinion they add too much bass if you aren’t careful enough with the volume.

Backbox speakers sounds SOO much better from FF but the sub really improves it. Unfortunately on Met the SAM system is only mono and uses only lower quality audio files.

Like said before buy the volume control as well. Leave the extension cord and coin door mount. You’ll set it up just once and it’s fine.
The 10” is delivered with anti-rattle tape but I didn’t need it. No rattle at all.

What is the purpose of the blue roll of plastic in the kit? It’s not mentioned in the instructions or parts list