The HKS downpipe is great for the price but it's not an ideal design in theory. The problem with the downpipe is that it has a flat flange just like the OEM downpipe. Some people tend to make a big fuss over this but the reality is that you're not going to loose that much power if any using the stock TD04 or most of the VF series turbos with the HKS downpipe. The next best choice on a budget from what I found would be the Helix downpipe for under $300.00 shipped. The helix has a bellmouth design.

flat flange (HKS, stock, etc)


bell mouth (Helix, Invidia, TXS)


twin dump (Vishnu, Bosal, B&B, etc)