Looks to me like the 86-88's are different enough that you need to read the plug afer the pipe change - most likely no on the pilot jet change unless your well out  on idle mixture - if you have the 3 groves on the needle you sure don't need the spacer mod - we're just doing it on '95 and up as our bikes are factory much leaner than yours and do not have and adjustable needle - I'd bet if you changed the pipe, did a k&n, up the main to a 157.5 or a 160 you'd be in fine shape, but a plug reads would sure tell you.

The part number jardine 14-4104-01 is the one - I see it in several places for as low as 135-140 + ship via google - I think the MACs are cheaper at around $100 - www.ronayers.com is a good source of parts and study - as they have the fiche online as do others - you need a new exhaust gasket as well.

Niether are going to be very quite - you just can't and increase the flow