Well i think im an expert by now after getting the Hyper rev mag.
What type is your stages? The Rb25s? If so go for 3" all the way including the dump pipe with seperate wastegate. As for prices it varies like heavan and earth. Dpends wheter you are brand consious or not.
f*kitsubo is like a mercs in its class very good and high quality. Although theres few other brand that you can get such as Tanabe, Trust (good price personally), Kakimoto, Dolphin (Rolls royce class) HKS(good price), Fujitsubo. Just depends are you brand concious or not like Tangles sais. No offence Tangles