Hastings/Baldwin has the best louvers.
The M1 slotted tubes are ok, even if not as good as Hastings. But Purolator you should avoid since they're not always punched out properly, like in Z06's images above.
So for me, it's round holes or Hastings
The M1 slotted tubes are ok, even if not as good as Hastings. But Purolator you should avoid since they're not always punched out properly, like in Z06's images above.
So for me, it's round holes or Hastings