when i got my u-bend delete, resonator delete, and high flow cat i got it all done at a shop. So i dont know what size everything is down their. i would think a 2.5 right??

The reason for me asking this is i plan on doing a smaller pulley (3.5) in the next few months along with the supporting mods that go along with it. but my main question is can i run a smaller pulley without the 3" downpipe. it is bothering me right now because if not i will have to spend more money to get all that work done down their and get that 3" downpipe so i can. i dont plan on putting a whole lot of money in the car just a couple of mods to make my car faster thats all. i have been reading through these posts and it seems as if i need to get the 3" downpipe setup to run that smaller pulley (3.5). i know i want to reduce that knock so im kind of unsure.

 

I would get under there and measure the OD of the pipe. Hopefully they used 3", but I would bet if they looked at the rest of the pipe- they probably would've just used 2.5".

I don't think its really a deal breaker as far as running a smaller pulley- assuming it is mandrel bent and not crush bent (stock gets down in the low 2.x" range due to double wall- and the stock ubend gets much smaller than that)- so even 2.5" wouldn't be terrible. However, a bolt in 3" stainless downpipe only runs like $60-80 shipped used from clubgp or similar forums- especially if you have crush bent, I would consider swapping it out.

The other thing is no one is going to be able to tell you if a 2.5" or 3" downpipe will allow a 3.5" pulley for sure. You really need to geta scan and have it record KR values- post your peak and average KR values (after you do your supporting mods, before you do your pulley)- and then we can help you make the decision as to whether you should ditch that 2.5" or not.