I had almost the same upgrades as you before with my wheels and had 249wrhp and 241 tq but I have the stillen exhuast. Your Borla exhaust puts out more power. The tsw's are very heavy.

 

The TSW's weigh slightly more than stock.

 

Just rim 8lbs more front, 11 lbs rear.38lbs more than stock over all. I was gonna buy these and saw how much more they weighed.

 

Oh wait, those were the 18"s that wieghed that(or were they the 19s, I know they only came in a couple of sizes,sorry guys got lost in this one), I don't know how much the 20"s were??? Sorry. Can someone chime in if they know how much they wieghed, I know they are lighter than alot of other 20s.
But who cares the tsw's is a nice looking wheel 2. For looks I'd lose a few horses anyway.

 

guys now am 100% sur 20" do hurt performance big time!
we went out me and some of my friends to race in a far away street where there are no cars ..
i started with the BMW 645 coupe ...first ande second he went in front and won by far ...3rd time i went in front till i hit 140 KM/H and the he passed me like a bullet !!!!...I was thinking about it ....and i said i shouldnt race that guy with my friend beside me !!! he was 105Kg which is about 200lb !!!
the second race was with a stock 5 speed mastang 2001 and we started he jumped infront of my 1 car length the when he put it in 4th gear i startid to come in when he put it in 5th i passed like he was slowing down !!!
ok i noticed later hehad no fule ....he was on E (empty)
i had 3 1/4 full 20" rims and a big *** supwoffer ..
so now am gono take the tube sub wofer out .....get on the stockes rims....and keep the 20"s for show only ....and gono race with only 1/4 tank full and am gono see what i can do .. am sure i can eat the stang .......!
i dont know about the 645 that car is fast !

 

There is a TV show called Sports Car Revolution on Speed Channel. These are the same guys from Dream Car Garage. They upgraded the wheel and brake set up on a stock RSX. I think they went from 16 inch stockers to 17 inch Mugens, a little wider of course. They also added a BBK, I think Stoptech. They did a base dyno run on the stock set up and then a second run after the wheels, brakes and cat back exhaust. They lost over ten horsepower at the wheels because of the greater rotational mass of the wheels and BBK. A 20 inch wheel set up definitely affects straight line performance. The trade off is looks.

 

Well just turn the boost up another psi to gain some more power

 

That's exactly what they did!