street twin or spec 4???

For the mods in my sig what clutch do you recomend, i'm on the fence here, i can get a spec 4 and flywheel for like 650 or a street twin for 1k, is it really worth the extra $400??? Given i don't think its going to get much more power thrown at it for the next few years unless i go with nitrous....

this is a good question. I'm trying to decide between the two myself. I was also wondering which is more street friendly?