One of the guys on here has a Nismo JDM with tiptronic box for sale. he also has one the same he is keeping. They are 2 completely different cars.
His one goes like an upreved HR on steroids and the Nismo is very slow by comparison. There are no known mods to the one he is keeping.
Maybe the previous owner just plodded about in town all the time and its all coked up!
Is there any noticable black smoke coming from the exhaust?