alright so my d15b7 as about 110000 miles on it and knocks a little the only thing iv'e done is stright back exhuast with no cat, ngk plug wires and a cold air intake.... The problem is that when i get on it i can smell either gas or oil, and i sont know if the oil is low cause the sip stick is worn to much> IF ANYONE knows whats wrong or if this is normal let me know also can someone tell me what kind of oil i can use and what the dip stick is supposed to look like

 

You smell gas either because of no cat or an exhaust leak. To me buring oil smells totally different than burning gas.