Maybe, if someone wanted to try. One would have to measure the diameter and length of the handle knob's post and see if it is a match to the aftermarket knobs that are currently available. That's what I did with my EVICT 2000 - and it worked out beautifully.
From what I can see, it looks to me like the little Slammer IV DX 2500 already has a round-ish EVA knob from the factory - probably to save weight, as you suggested.
Now here's something, the price of the new DX 2500 will be $289.95. This is like $80 more than the Clash II 2500, which everyone seems to agree is a darn nice reel. Are the stainless steel gears (and sliver color vs the Clash's murdered-out black) worth that extra money? Well, that's a personal decision, right?
Doubly so, when the Tsunami EVICT 2000 with its truly excellent stainless steel gear set sells for pretty much half that? Is the Penn name worth double the Tsunami name? Maybe. Again, a person decision. Hey, both are made in the Far East, so there's that. I have to say that two seasons with my EVICT 2000 have shown it to be a really, really nice piece, Zero issues and oh so smooth. John at Trophy Tackle talked me into my EVICT - and I am grateful that he did. John knows things . . .
