I've had a rattling heat shield for the last year. When I got my 245 I think the rattle was slight then, but the welds finally all popped off and since then the cursed thing has rattled loudly, signalling my approach as if I was Fred Sanford in that crappy red pickup. Well, a friend who works at a garage cut the thing off for me tonight, and man is the difference heavenly. Plus I no longer have to worry that my cat might be disintegrating, since the exhaust no longer makes any noises other than normal ones. Now for my question: I've been thinking about putting in a K&N filter but I'm wondering if the horsepower increase claims warrant the price of the filter. If I'm right, does the K&N filter for a 200 series consist of simply the K&N version of the regular paper filter. If so, how can they claim something like 10 - 12 hp increase when you're not increasing air flow into the filter box? The K&N supposedly passes air better than a conventional filter, but that wouldn't seem to make much if any difference unless you increased the size of the intake going into the airbox. Right? Maybe I'm wrong. I'm not a major gearhead, but I just want to know if a $45 filter is worth it. What do you guys think?

Matt Campbell '87 245DL 194k and runnin' strong

With the K&N (or AMSOIL) air filter, the only place you will see a difference is at top end. Think about it--the amount of air is measured before the fuel goes in. Under normal conditions, there won't be any appreciable difference. Since these filters will allow more air through, it is possible to get a bit higher top speed or a bit more power under extreme conditions.

In most cases, you probably won't notice anything different, except the filter will last longer.

The AMSOIL filter will keep out more dirt than will the K&N.

The K&N filter is a good option. It is a cotton filter in a wire mesh. Your looking at more like 2-3 HP increase if that. But, when coupled with a sport exhaust the difference is much more pronounced. The K&N lets much more volume as well as cut down the turbulance in the intake by straitening the airflow into the throttle body. 45$ is alot but remember you will never have to buy another filter and it will improve your mileage.

The Amsoil filter will do about the same thing.

When they quote a 10-12HP increases, they're talking about a big-block V8 or similar large-displacement/turbo engine that sucks a lot of air.

That said, it may give you somewhere between 2 and 5HP. I got one, and I did some modifications to the airbox to improve flow. End result is a little extra oomph at high RPM, a little better throttle response, and a good bit more induction whine.

The drop-in replacement is a direct replacement for the paper element. The other option is to use a cone-style K&N and adapt it to your intake tract somehow.

A 10-12 HP gain is probably a generous estimate with the addition of only a K&N air filter. If you did some kind of airbox modification, you might gain a noticable difference, but I can't say for sure. I tried to buy a K&N for my '87 244 from IPD, but it was on back order and then it didn't come in when it was supposed to, so I bought an AMSOIL air filter instead. The AMSOIL filter seems like a very good quality filter consisting of oiled foam (instead of oiled gauze like K&N), and it's supposed to allow air flow better than a paper filter, and catch as much or more dirt than a paper filter, which would seem to help a lot if the air flow was increased. The total cost for the AMSOIL filter was $37.00 and it comes pre-oiled and included a small container of oil.