ive ran on my 88 the stock one a pro circuit and a fast 50s all have been good in there own ways, the difference between them has been they all sound different and tend to have their peak power in slightly different places. im currently testing the difference between the big bore fast 50 and the small bore fast 50 pipes.
but any one you get you will be happy with im sure. Get the one you can afford or you like the look of the most.
Unless your racing and chasing every bit of speed you can it probably doesnt matter too much
The Best Suited Pipe Ive spoke about with other guys who Ride 88s is the Dr.D Pipe...but FiveO Podium's suit well for 88s as well but yeah comes down to personal choice and how much your willing to spend in the end.
But I wouldnt recommend the 4.1 FMF for an 88! Especially if your Motor is an 88 Limited as the diameter of the hear/pipe on the 4.1 are huge, too big! There more Suited to 106+cc Honda's.