E39 Conversion

[GP5]

I own an E39 1997 single vanos 5.28i. The triptronic gearbox packed up and so I opted for a manual conversion.
Reason....
Because I also ordered a G-Power EVO I supercharger. The auto box would give 270bhp as opposed to the manual box which will allow me to boost the supercharger to 300bhp.
I have yet to install the SC because I am having problems with my manual box.
Currently the 2nd gear pops out and grinds a little when I select 2nd. Why is this? Is the gearbox damaged or is the liunkage the issue?

Also
I installed
Headers
Race cats
and rear box from G-Power but the noise is very loud and tingly! Is this because I need a silencer to be added?

Please please can some-one advise as I only have a limited time to return the gearbox.......

[jllphan]

Maybe you will have more luck finding an answer here. Wish I could help...