Stock 98 V-90 exhaust how restrictive?

[RCR]

I had my 98 V-90 upon the rack at a local shop yesterday. The shop guys were looking at the system telling me to leave it alone.
There is no room for larger pipe around the IRS in the rear and they say the center muffler is straight through and not restrictive. I'm agreeing with the no room for a larger pipe without rattles in the rear over the IRS but the stock center muffler?
Anybody done a performance exhaust upgrade on one of these cars? How much of a MPG and performance gain did you see?
I'm thinking of just doing a removal of the center muffler and then going to something maybe like a Borla here. Is it worth it in HP and MPGf??

[Hit Man X]

I too was interested in some extra performance from my V90. The 180hp/200tq or so from 2.9L seems pretty low considering it has a 24 valve head with modern port EFI and decent static compression despite being an undersquare motor. Obviously the early cams work for 20hp or so. Just get them from a used car to save cash. No idea how well blocking the stock heat riser works, but it cannot hurt.

Spoke with an internet acquaintance from a BMW site, who is into Volvos. He said the V90 had a poor exhaust from the manifold collectors on out... just like most Volvos. Which is odd as most Euro cars are pretty efficient leaving minimal power on the table. He claimed someone picked up 44rwhp with a full exhaust. But I am not sure if that was paired with the early cams or not. Either way, that is a very significant power gain.

I was told, the head pipes into the cat appear to be ~1.75" (more than sufficient for the power) BUT they are double walled shrinking them to 1.5" or so ID. Not what you want. I have no idea how well/poor the round resonator flows, one would think well but doubtful... same goes for the rear muffler, it is probably the typical reverse flow crap. If the stock system proves to be crap (i.e. I find some concrete data to support this) I am going to do dual 2" from the manifolds into a single cat (DI/SO) that drops to a single 2.5" out. Utilizing a long Diesel style muffler for the resonator then a good rear muffler that is similar in size to the stock rear. I have had good luck with Magnaflow products as they are stainless steel.

But again, if this only frees up 15rwhp I am not going to waste my time as the cost for the power gain is not there.



Seems to me if there is someone to tune the PCMm some larger gains would be yielded with the hotter cams.