The following articale was posted to the BMW digest by me in July '96.....

At long last the K&N cone filter for my 318iS arrived last week. Alas a rubber hose supplied with the kit was the wrong diameter. K&N supplied a replacement quickly and efficiently, turns out they only just started making these kits in the UK and I bought one of the first. Their supplier delivered a few hundred hoses of the wrong size it seems.

Instructions for fitting aren't bad but could be better 6/10.
Build quality is good overall but not up to BMW standards 8/10.

The first problem I hit concerned the four bolts which join the air flow meter to the existing upper air box lid. These have to be removed to accomodate flush fitting screws supplied with the kit. The bolts are a cast iron SOB to remove, I tightened two bolts against each other and turned the bottom one anti-clockwise to remove the double threaded bolts but one broke and I spend two hours trying to remove it. Clearly removing these bolts is not K&N's fault but it would have been nice if their design could have just reused them!

Second problem is that the AFM (air flow meter) sits further forward in the engine bay by about 6". The AFM cable doesn't have a lot of slack and in my car was slightly taut when plugged in, not good. I'm going to cut 20mm off the K&N rubber hose which connects the AFM and existing BMW air intake hose and I'll also drill a new hole in one of K&Ns mounting brackets 20mm further along, this should relieve the stress on the AFM cable.

Third problem was that my after-market alarm is mounted on the inner wing near the air intake, quite common I believe. It just touches the cone filter housing but hopefully moving the lot 20mm back (see above) should fix this. Check clearance before fitting to avoid dissapointment.

K&N supply a flexible expandable aluminium pipe (you know the stretchy ones) to blow cold dense air over the cone filter. They suggest the outside end of this is connected to the lower spoiler below the front number plate. I wouldn't do that, more than once that part of my car has been in deep puddles and I don't think scooshing water over the intake is a good idea somehow.

So many problems? The results are worth it :-) The car makes a lovely roar under hard acceleration and is smoother throughout the rev range. Power increases are really noticeable above 3000 rpm and at 4500->red line it's like a different engine, very willing.

I can't quantify the performance increase but it definately brings on an instant ear-to-ear grin. The kit cost 84 GBP and is worth it. It fits the M40 and M42 engines and needs little mechanical experience to install. I'd definately do it again.

When I removed the filter after 5000 miles of town and country use I found no evidence of poor filtration, a common worry. I rubbed my finger along the AFM intake and it came away clean. I find that in Scotland the aluminium tubing duct makes no difference and have removed it. In Warmer countries this probably isn't the case.

It cost 84 GBP including VAT and was well worth the money. I think my fuel consumption may have improved very slightly despite the fact I'm driving faster!

Recently the support bracket snapped off, just too much weight on it.

When I got my 89 318iS I didn't fit a cone due to the mounting hassles. I used a K&N panel filter instead, this makes very little difference though.

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