well it has a big ass computer in the boot but it shouldnt, i think stock from wheels magazine it was clocked at 8.3seconds to 60mph for the manual model (92 si 4ws)
I have an auto and have gotten 8.5, I think 7seconds is asking a bit much but with the right mods Id say it is possible.. high mileage does count, I have 186,000k's not miles and I have noticed that my engine isnt as strong.. maybe cos I have driven it to strong in the past or it needs a good service
at the end of the day if you thrash your car the engine will get tired but if you drive it like grandpa service it regularly it will stay in top notch condition