I'm pretty sure something like this has come up alot so I'm sorry to be bringing it up again...lol....I have a 91 FC3S Convertable and I've been look for a way to put a cold air intake system and I've seen K&N make them up to 1988. It looks like it replaces the stock air intake piping up to the air filter box. Since the 1988 has the same engine shouldn't it be able to fit onto a 91? Here's the link. Once agian I'm sorry to be bringing up something that probably has been brought up many times in the past.


http://www.car-stuff.com/performance...5&skipped=true

 

way to expensive for mee.....not worth it for the price....im my opinoin...you can get the tube and the filter from ebay and make your own intake box..itz cheaper......if you want true cold air...do some search...the 92 honda prelude intake pipe can help

 

the engines aren't the same, but that doesn't really matter, what would matter is that the AFM changed between 88 and 89 and after 89 there is a circular attatchment to the afm instead of a rectangular one with 4 bolts. I'm not sure if this would work, the actual box would pobably work fine, but you might need to but a different cone filter or use some enginuity to hook up the one it comes with.

 

Yeah, you need an adapter to attach your typical aftermarket filter to the S4 AFM.

It's not hard at all to make your own. This is mine, I removed the washer fluid reservoir and expanded the neck hole to get the fresh air tube in there: