Please keep in mind that Penguin/Penguin B filters use water flow to operate the bio-wheel and keep it turning so you shouldn't reduce intake flow because it will reduce biological function.
The best of the single wheels imho is the 150b but its intake power is enormous, I had a girl who ended up crushed around it and lost her swim bladder then spent the next five months powering to the surface and gliding down. My fixes for the 150b include the intake from a 200b, always using the mid-level intake with a ring of sponge around it AND running a pair of pins up through holes in the output plate to put a line of poly needlepoint grid into the flow.
With betta I'd ALWAYS get an intake sponge of one size or another, if you need one you can cut-to-fit the Cascade internal filters have replacement sponges up to one nearly four inches square by seven tall with a small hole down through it.
The penguin 200b tho is an odd case problem, thanks for bringing it up!
My 200b is now a backup filter because when it is dirty it only moves about 160 to 170gph. The bio-wheel stalls constantly and can't even cope with snails. As a mechanical and chemical filter it is awesome, the double slot and the addition of being able to use baskets made for it really help a lot but it simply lacks the ability to intake enough water for any margin of maintenance. One modification that can help is an E shaped baffle just before the bio-wheel that forces the water into two higher streams but I figure that's just a stop-gap not a reliable fix.
I'll be honest with you, if you like the 200b and need that level of filtration, splurge on an Emperor 280. They come with a large carbon basket that you can put cut-to-fit filter material in front of and never have to buy another disposable filter. They do stick deeper into the tank lid space than the 200 but not by much. The benefit to the 280 is in the way it was made.
It uses the intake strainer from the emperor 400, a spray bar to operate the bio-wheel and has a large vertical output to play with.
On my 280's I put them at the end of my 10 gal tanks with just one modification. Using nylon bolts put through holes from the back of that large vertical plane I make layers of the poly grid slid onto the bolts with nylon nuts separating the layers. This not only slows water speed but spreads it out into a large wall of slow moving water while still keeping flow. It also gives a small boost in surface area for biology AND the water drops in behind it pulling bubbles down through the grids. My tens are both swept clean by this full smooth flow of water across the top and back across the bottom but even my oldest girls have no trouble swimming.
I sincerely advise people to check out making baffles with the poly grid but be careful not to leave any broken bits that may come off in tanks, betta try to eat anything
I get the nylon bolts and nuts at Home Depot from the bolt and nut drawer, stainless is an option but will slowly add nickle and iron to the tank. Don't use iron, brass or aluminum.
Hopefully I'll have a nice camera to take pictures with today and be able to show all these modifications.
Excess current in the water can kill your betta, remember that they are effectively holding their breath all the time. Their response to current is an instinctual one to not change position, not necessarily frolicking in flow, they live in mostly stagnant water with established biology so a sudden wash of water is a risk of losing their home in the wild.