No it's not on performance or appearance etc just i hit a spot of bother again with a part ordered online,a Mugen thermo fanswitch to be precise as my original one has kicked the bucket but upon arriving from Japan i suspected it wrong as the nut size was different(22mm) and my old was a (24mm) but i went ahead and hoped it was just the nut that was different but it wasn't that easy,the Mugen one is just too small and pops in and out of the housing .

Cross checked the part number and yep it says Prelude both 4th and 5th gen compatible i'm sure so i got back to the company i bought it off and they have checked with Mugen and said "if your Prelude is Australian spec, it could be different from Japanese spec as the parts we are selling are all designed for Japanese domestic model, so we can’t guarantee if the 37760-XK5-00N0 is compatible with your car or not"

The 37760-XK5-00N0 switch is another Honda fitment and i came across it on a shop's site saying that was for the Prelude 92 onwards but Mugen cannot confirm it is on their fitment list for that part number,aargghhhhh!!!!!

I had this before with an aftermarket rad cap from the US,ordered correctly and got the longer cap but i needed the shorter fitment,took 2 weeks to exchange and my old was leaking too.

Meanwhile my car is pretty much lying up.

There is alot to be said for buying online and most of the time it is cheaper,Honda wanted near $115 for an oem replacement and the Mugen was $85 and whilst i had just upgraded the radiator it was a good addition.

Waiting to see if they can find out if the other one is a 22mm nut then hopefully exchange it.

If another prelude owner can confirm that there's is a 24mm nut too,that would help,i wouldn't have thought that my cooling thermo housing could have been exchanged though the years but it wouldn't surprise me .

It's a 94 BB1 H22a1 Vti-R.

Cheers.