I have a 91 rs with 350 tbi and 700r4 and i was wandering if i put 4 10s in how much topend speed will i loose and how far off will the speedo be

im not sure about the top end speed but a friend of mine has 4.10's and his speedo is off by about 15-20 mph

if you have no shift kit, top end will really suffer, i have 3.73 in mine and my top is not great,but i am putting a shift kit in to try and solve some of it, before turning to the engine to fix it