My two cents...
I had an M&K 2/1 on my 87; plusses are 1) it is a good deal lighter than the Fabspeed and 2) less expensive. Ben at M&K is great to work with and the quality of his product is outstanding. I still have an M&K and SSI on my 79SC- changed the cams out too- all of which add to a possible downside in a cab: it is pretty loud. Ok, it howls...which, in certain circumstances, is pretty cool!
Since I had cool and loud covered, on the 87 I swapped the M&K out for a Fabspeed- much better sound than stock. With with factory hx and cams on the car, the M&K sounded "tinny" when you get on the gas, whereas the Fabspeed is deeper and a bit quieter. Just my opinion.
And Steve Wong's chip is super upgrade!
Best-
Matt