TWM lists two air horns for the Japanese SU.

1 3/4" with

44 mm Air Entry 2700-4450 44 50 88 FR

1 3/4" with

48 mm Air Entry 2700-4850 48 50 88 FR

Which should I buy to pair with a pair of ITG air cleaners? MSA sells some too but I have heard they are smaller than stock air horns. I believe the MSA ones are by TWM.

Sorry double post.....Mods please delete.

Send escanlon a PM he put one on his Z

It's powerful !

TWM lists two air horns for the Japanese SU.

1 3/4" with

44 mm Air Entry 2700-4450 44 50 88 FR

1 3/4" with

48 mm Air Entry 2700-4850 48 50 88 FR

Which should I buy to pair with a pair of ITG air cleaners? MSA sells some too but I have heard they are smaller than stock air horns. I believe the MSA ones are by TWM.

Umm as I recall the aluminum horns that MSA sells are the ones for SU's, (they also have a steel set for triples i believe)

anyways, for stock SU's 44mm should be the right ones. I went thru this trying to match up something for my bored out SU's, i even went to MSA and measured those aluminum ones, they measured a bit too small , like 41 or 42 mm ish..so I ended up going with the stock air horns...((thats why I could only send you the outside of the air cleaner)) I extracted the stock ones from the inside air cleaner plate because they measured out larger than the aftermarkets. I also was unaware that TWM made a set of 48's for our SU's, sigh...

Umm as I recall the aluminum horns that MSA sells are the ones for SU's, (they also have a steel set for triples i believe)

anyways, for stock SU's 44mm should be the right ones. I went thru this trying to match up something for my bored out SU's, i even went to MSA and measured those aluminum ones, they measured a bit too small , like 41 or 42 mm ish..so I ended up going with the stock air horns...((thats why I could only send you the outside of the air cleaner)) I extracted the stock ones from the inside air cleaner plate because they measured out larger than the aftermarkets. I also was unaware that TWM made a set of 48's for our SU's, sigh...

So the MSA horns are smaller than stock. I was told the ones MSA sells are by TWM.....If I get the 44mm ones from TWM will they be the same size as stock air horns?

http://www.twminduction.com/AirHorn/AirHorn-FR.html

Bump...........

TWM says usually 48mm is the correct match.... Can anyone here verify if it is 44 or 48mm?

Measure the size of the horn on the stock air cleaner box. According the Ztherapy the stock plate with the intigrated air horns gives better power than the aftermarket horns. They claim to have done test but I have not ever seen a graph or chart. I doubt the difference is really noticable though.

Pam with Z Therapy says 44mm is the stock size.

Update: David Spillman measured his stock horns and he agrees with Pam that the 44mm ID is correct. The set he said were smaller than stock came from VB not MSA. I know TWM sells a 44mm. Got to see what size and style MSA sells in conjunction with their ITG filters.

MSA sells TWM 44mm ID air horns as well as the dual ITG air cleaners to match. Probably my next purchase.