1/8 inch gap on either side is correct. it is done in order to obtain an even pressured fit around the turbine. just make sure that you have 1/8th on each side as oppsed to 1/4 on one side and none on the other. Also be careful not to tighten the bolts excessively, as the are steel and they thread into aluminum.

Regards,

Jason Burg / JetCat USA Techinician