Wanna borrow my 105mm Accufab Race TB?
Seriously, Lee is right. Doesn't take much with a die grinder. And if you don't have a die grinder, this is a perfect reason to go buy one!!
Here is a pic from when I opened up a Vic 5.0 to accept a 90mm...
http://www.the-arnolds.net/Cobra/vic...Port-Match.jpg
You can see (hopefully) that I just put ~1" transition there.