Here's an easy fix to prevent your replacement K&N tube from cracking AND it will prevent the short 1/4-20 set screw K&N provides from coming loose, falling down the throttle body and doing BAD things!
The top piece is the stock K&N shouldered nut. I cut it down to 2.80 inches and cut a piece of 1/4-20 all thread to 3.75 inches.
Using a 13/64 drill I made a pilot hole through the shortened shouldered nut. Don't worry if you damage the threads a little, you can clean them up with a tap, but don't completely destroy them.
Flip the shouldered nut and enlarge the pilot hole using a 1/4 inch drill bit. Run it down until you just touch the top of the threaded portion.
Clean up the edges with a countersink.
Double nut the 3.75 inch long piece of 1/4-20 all thread and LIGHTLY bottom it in the throttle body.
Thread the shortened shouldered nut over the all thread and LIGHTLY bottom it against the throttle body.
Depending on your throttle body and which nut you use to hold the FIPK body you may have to adjust the length of the all thread or the shouldered nut. With the stock throttle body the shouldered nut will need to be about 2.60 inches long, but MEASURE TWICE, CUT ONCE!
This mod will also keep your FIPK from cracking the tube because the head of the shouldered nut now supports the tube so it can't be overtightened.
Install either the old stock plastic air hat nut or something like this spiffy F&B nut. Make sure the K&N tube is held firmly against the throttle body gasket, but is not being deformed because the modified shouldered nut is too short.
Remember to measure before you just cut using my measurements. The K&N tubes are not very uniform. Just screw the piece of all thread into the throttle body and put the K&N tube onto the throttle body without the airhat gasket. Mark the all thread, remove the K&N tube and measure from the throttle body to the mark on the all thread.
Nolan
