A shroud is an absolute must for in town driving no matter what type of radiator your running. Can't comment on whether or not you need a new radiator since you didn't describe your current one but if you were thinking an aluminum radiator by itself will solve the problem without a shroud my guess is I highly doubt it. Remember, air movement is what cools. If your putting in slow traffic your not getting much air flow through the radiator, even if you have a fan.
