hi people my w202 has a 1jz under the bonnet for a couple of years.
and I have two main issues that I couldnt solve.

1)
Car is a 96 c220 and I am not sure what the diff ratio is. It is now matched with 1jz box and the ratios are screwed.
speed/7000rpm for each gear:
1st: 96~98kmph
2nd: 166~168kmph
3rd: 240+kmph
4th: cbf
as you can see the gears are pretty damn long. It has barely 3000rpm while cruising at 180kmph.
It was however still very nice to drive with the 1jz and stock ceramic twin turbos that spool instantly.
although 0-40kmph is a little sluggish, it was still acceptable and managed 6seconds 0-100kmph with the stuffed ratios. (with proper ratios and 1jz stallie it should hit 5seconds)
the real problem came when I replaced the stock twins with bigger HKS twins.
the car has absolutely NO POWER anything under 60kmph. (tho when it pulls it pulls hard)
the turbos hit full boost (1.1bar) at around 3800rpm, which is pretty good for the power they can produce.
however due to the ratios I will be doing 60kmph at 3800rpm @ first gear.
the car is very sluggish from a standing start, but its fine when the car is moving already.
so question is, is there any differentials with a 4.0 (or anything above, 4.3 with LSD preferred) ratio that will bolt straight up to a w202?
I have seen people modifying the flange and diff cover so they could use the diff from other models or makes.
but how reliable will that be? longshaft and subs will need modifications too i suppose? anyone here done this before?

2)
I understand there are a few turbo'd w202 on the forum I am wondering what are the sizes of your frontpipes?
I have been wanting to upgrade my dumps and front pipes but there are metal bars in the way and my 2.5" barely fits in. the metal bars (from the body i think) form a square which my front pipe went thru. I have 3.5" all the way to the back after that "Square" spot. I really want the bigger twins to breathe better so it would be nice to see if you guys managed a bigger front pipe.

sorry for the wall of texts but i think its better to give as much info for easier understaning.
any thoughts?