Not much compared to just using the right Keihin Jets. It comes with a different tapered needle which may be nice.. and a lighter spring. But, you can shim the stock needle and clip the stock spring and get pretty much the same affect.
I did the above before getting the dynojet kit. Then for S&Gs I bought the DJ kit... Hardley noticed a difference for the "free" mods. So, it would be nice to be able to get just the needle for $15.. maybe Alba will have one for sale seperate one day.
You can buy the needle or spring right from Dynojet separately. But you have to use all the same brand together. Their needle is designed for their jets, the stock one for the Keihin jets. Doesn't matter with the spring though.
That's why Dynojet will tell you to get you to buy the who kitnkaboodle. I examined the jets and needles... they're not different enough to matter. I've used keihin/mikuni with dj needles before with no problems.
Dynojet is almost as bad as some honda dealers I've been reading about with feeding people false info to make a sale.
I have read most all of the posts here and have been wondering why everyone is wasting there money on the dj kit. I bought one for my 400ex when I first began to modify it and it was junk. It consisted of basically an adaptor that allowed you to run minkuni jets in a keihin carb, a bunch of minkuni jets and a needle.
The adaptor broke during the second jet change so I gave the jets to a friend with a yamy and bought a bunch of single keihin jets from my local dealer for $1.50 a peice. The stock needle on th 400ex is adjustable so I just used it until I bought a Lectron carb.
I received a DynoJet kit in the mail today with a K&N Filter. I believe that I am gong to send the filter back and get a UniFilter. I was hoping that the kit would come with a box with separate compartments, like the pics on the website. I am going to do the exhaust mod to a 1-1/2 or a 1-3/4 outpipe. I am also going use a 144dj main jet with the needle on 2 or 3 as a starting point. I will probably do this in the next couple of days.
One question, since it is so cold due to the front, will I have to rejet after it warms up to the 60s next month?