hi i want to ask iam going to fix y pip so the stock one is 2.5' so the new one should be 3' to go for the hp?cause i will chage the complete exhaust

 

I'm not quite sure what you are asking, so I'll assume you are asking if a 3 inch y-pipe would be better than the stock 2.5" y-pipe. Well, it depends on how much you plan to modify your car. If you just plan to put on an exhaust an a few other mods, then a 2.5" y-pipe should be fine as long as it is mandrel bent. The main problem with the stock y-pipe is that it is crush-bent, not mandrel bent. For naturally aspirated cars, I'll bet a 2.5" inch system is fine. If you plan to do forced induction, though, then a 3" (or bigger) exhaust is better.

However, most of the aftermarket y-pipes are 3". If you get one of those then you'll want to get either a complete 3" exhaust system, or a b-pipe which has a 3" connector on the y-pipe side and a 2.5" connector on the muffler side.

 

yes caus i will have complete 3' exhaust system and i will post the pictures when it finsh