Hello

I'm sure these questions have been asked before but I might be getting a mk2 focus rs fairly soon.

The car im looking at has a full miltek? Turbo back decat exhaust.

The engine warning light is on and the owner said it came on 70 miles after fitting the exhaust due to the decat?

Does this effect running? How do you turn the light off without fitting the standard exhaust back on?

I used to have a mk1 focus rs and had the same problem and the boost used to limit while the light came on, you could disconnect the battery for 10 mins put it back on and you would be back to full boost for another 100 miles, is this all the same with the mk2?

Can you disconnect the battery on a mk2 to turn the light off like the mk1?

What should a standard car boost to on the boost gauge?

Thanks

James