What kind of boost guage are you using? Maybe its not a turbo/wg issue at all and simply a fubar guage.

 

OK, I checked thw Wg, it works fine, no obstruction to flow. But this is what I think may be the problem. The flange's outlet that ive welded to the exhaust manifold is 4-5mm smaller than the ihi RHB5's inlet. So what I am thinking is that small outlet is restricitng flow to the Wastegate. I tried porting it a bit, it took 20 mins to take of 1mm, but I noticed the boost wont climb past 7 psi. Still alot considering the WG is fully open, but maybe if I completley port match it it will boost 2-3 pounds? Have any of u guys had this problem before?

 

I havent read everything.....I had the same problem with my first turbo..
Small turbine and small wastegate hole...the exhaust gasses will be so much that it can't all go thru the wastegate hole....min boosted to 15 psi with the wastegate open, but it only happened at 6K+ rpm's. get an external wastegate...right now I have a T3/T4 and I just bought an ex wastegate, cause the internal one of mine isn't working very well,

 

Ok guys, I am really stumped on this.
I bought a new boost guage and it shows 9 psi in 4th gear at 5500rpm.
Has anyone else here used a IHI RHB5 and had the same problem? What If I enlarge the WG port? anything?

 

ttt