Phillip Austin

Trying to figure out if exhaust is oem. I see no identifying marks or anything on tips or muffler etc..

Back tires are 275 35R20 and front are 245 35R20
are these sizes good for acceleration and taking corners fast? What size is best recommended?
thanks in advance

Z28KLR

Regarding the exhaust question we'd need to see some pics....

On the other question, that wheel and tire combo is sacrificing a little bit in acceleration, and since I'm yet to see any road course cars set up like that then I will assume probably sacrifices a little bit there too. An 18" setup would probably be optimum regarding those two things, although of course tire choice really comes into play here. With the right tires there's no reason you couldn't make it do what you want with those 20's, and steeper rearend gears would offset the taller diameter of those tires vs the stock 17" or 18" your car came with.

I've driven a few '05-'09 cars over the years, all with manual transmission. Factory gearing options were 3.31 or 3.55, but from the driver seat the two were indistinguishable for me. I'm of the opinion that if I had one of those cars that one of the first things I would do is swap in a set of 4.10's. But keep in mind that your choices there need to be considerate of whatever your goals and intended use for the car might be.

Z28KLR

Typically for optimum turning related dynamics you would want a "square" wheel and tire combo. Meaning, same size at all 4 corners. Offset wheel/tire combos such as a typical for these cars 18x9 and 18x10 (275/40 front and 295 or 305/35 rear) can contribute to understeer, although honestly under most driving conditions you would never notice it. On a road course track where you really have the freedom to push the car is about the only scenario where you might find understeer to be of any hinderance. On the street, say a twisty mountain road or whatever, of course you can and will observe understeer (which these - like most cars, have some tendency towards) but unlike a track I think it's safe to assume you wouldn't be pushing the cars limits as hard and therefore I would consider the offset wheel/tire setup and whatever limitations it presents to be a non-issue.