Dude.. I reckon a 30 db clean in your Fx loop is what you need.. the OD sort of pedal's can do good thing's but boss is noisy,and doesn't really do it for me.plus isn't the OD-3 more higher gain?. the Clean boost will just up your volume and it's great for soloing.. i do it with my C+ and my mk IV.. but for putting pedals in front end ts-9/ts-808 or BB are the best.. nice and quite and very well suited to the mk IV..
The OD-3 is a great pedal. It's probably the best thing boss has ever made IMHO. However, it's not a boost overdrive pedal. It's a stand alone overdrive unit. Used as a boost, it sounds pretty close to what you'd get by using a DS-1 as a boost and that pedal is a lot cheaper.