If you don't have to retard the timing on the car due to detonation, you should gain around 80whp from the deal. So you're looking in the area of 200-230whp on the bottle. Many factors as Im sure everyone knows, come into play with this, so results vary.

Colder plugs, backed off timing also help fight off detonation - as Im sure you already know. Just find a good tuner who knows what they're doing. The only problem is, with some band-aid or lower costing EMS' you're sacrificing off bottle power for a good tune. If you have something such as Hondata, with nitrous control, or AEM EMS, then it is a non-issue. I don't know what other EMS' have nitrous control on them.