i got a 93 si vtec equipped with an '01 h22a4...now my issue is an overheating problem. the car only overheats when i come to a standstill after having been going for 45 mins on highway at the 65-70 (in the middle of summer of course). now i know the h22a1 is what originally comes with my car but the previous owner replaced it with an A4...i understand that these two engines are almost identical in terms of displacement, but when i ordered a new thermostat for my car the thermostat was for the A1 and was smaller than the one in my A4. which leads me to question, is the cooling capacity for 93' A1s compatible with '01 A4s?...i've been checking online for radiators for both '93 and '01 and there is a slight difference in size, although both engines are similar in displacement? could this be why my car is overheating on hot days and during traffic times after highway driving?....thanks for your help.