Hmm
looking that turret link, I think there's a flaw in the concept. The cards shown offer 4 attack dice, but only crits count against fighters. The flaw is that the Falcon clearly took no hits in its run into the trench to back up Luke, which these card rules as stated would make unlikely. A better solution might be to alter the potential dice roll of the turrets depending on target size:
2 dice vs. small craft
3 dice vs. large craft
4 dice vs. huge craft.
Or, recognize that the turbo lasers are intended to fire upon capital targets as a group, and thus it's not that they're more powerful in attack but that they can amass more hits at once against a single large target, which they can't do on a smaller, nimble target. So maybe they're really only Attack 2, and only effective at Range 2-3 (unable to bear at range 1). This allows for nimble craft to dig in close and "outrace" the turret (in abstraction). And of course, the target still gets the extra evade die at Range 3, while the turbo laser never gains a bonus attack die.
Actually, here's what I'd make 'em:
Imperial Turbo-laser Turret (Tower)
Attack 2
Range 2-3, no Attack bonuses possible.
Shields 0
Hull 3 (sorry, but the film clearly shows these things blowing up with only a few quick blasts from an X-wing.)
Imperial Turbo-laser Turret (Surface)
Attack 2
Range 2-3. no Attack bonuses possible.
Shields 0
Hull 2
Cost for both designs should be very low, 'cause they're crap against fighters. Maybe like 5 and 4 points respectively. "But you could field a ton of 'em at that cost!" Yep. They're all over the surface of the Death Star, remember. Heck, they crammed 'em in the trench shaft! So obviously, they're dirt cheap. The danger is the mass of them, not the individual nature of them. In the film, the vast majority never hit a single fighter. The implication is that Porkins more or less got overwhelmed by the numbers when one lucky hit gave him problems
Rebel Turbo-laser Turret
Attack 3
Range 1-3. No attack bonuses.
Shields 0
Hull 4
Rebs build hardier stuff, folks. That's a given. Cost is greater, though— say 8 or 9 per, maybe even 10. Good stuff just costs more (plus, the Rebs have limited resources to allocate, so the effect is higher cost).
This is off the top of my head, so consider that.
I do like the suggested idea that the turrets have to be aimed
but that's a lot of turrets to aim, so maybe the 360° should be retained, with no aiming function, so as to avoid slowing down the scenario.
The BGG guy's "only Crits" rule might work, too.
But in the end, IMHO, the turrets should be an inconvenience to the enemy, not a major threat. The game is supposed to be a dogfight game, not a tower-defense game. Whether Imperial or Rebel, the turrets should be mostly ineffective against small craft— otherwise, why have a fighter squadron defending a base?